AFE4404 [TI]
适用于可穿戴设备、光学心率监测和生物传感的超小型集成式 AFE;
| 型号： | AFE4404 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 适用于可穿戴设备、光学心率监测和生物传感的超小型集成式 AFE |
| 文件： | 总87页 (文件大小：1468K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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AFE4404
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
AFE4404 用于可穿戴光学心率监测和生物传感的超小型集成 AFE
1 特性
2 应用
1
•
发送器：
•
•
•
•
•
光学心率监测 (HRM)
心率变异分析 (HRV)
血氧饱和仪（SpO2 测量）
最大摄氧量
–
–
–
支持共阳极 LED 配置
动态范围：100dB
6 位可编程 LED 电流最高达 50mA（可扩展至
100mA）
卡路里消耗
–
–
可编程 LED 接通时间
3 说明
同时支持 3 个 LED，适用于优化型血氧饱和度
(SpO2) 测量、心率监测 (HRM) 或多波长 HRM
AFE4404 是一款面向光生物传感 应用的模拟前端
(AFE)，例如心率监测 (HRM) 和血氧饱和度 (SpO2) 测
量。该器件支持三个开关发光二极管 (LED) 和一个光
电二极管。光电二极管的电流通过互阻抗放大器 (TIA)
转换为电压，并使用模数转换器 (ADC) 进行数字化。
ADC 代码可使用 I2C 接口读出。AFE 还配有带 6 位电
流控制的全集成 LED 驱动器。该器件具有宽动态范围
的发送和接收电路，有助于感测超小信号电平。
•
接收器：
–
以 24 位二进制补码格式表示光电二极管的电流
输入
–
TIA 输入端的独立直流偏移减法 DAC，用于每
个 LED 和环境相位
–
–
ADC 输出端的数字环境减法
可编程互阻抗增益：
10kΩ 至 2MΩ
器件信息(1)
–
–
动态范围：100dB
器件型号
AFE4404
封装
封装尺寸（标称值）
2.60mm × 1.60mm(2)
动态节能模式，可使电流降至 200µA 以下
DSBGA (15)
•
•
•
脉冲频率：10SPS 至 1000SPS
灵活的脉冲排序和定时控制
灵活的时钟选项：
(1) 如需了解所有可用封装，请见数据表末尾的可订购产品附录。
(2) 请参见图 99 中的尺寸 D × E。
–
外部时钟：
4MHz 至 60MHz 输入时钟
–
内部时钟：4MHz 振荡器
•
•
•
•
I2C 接口
工作温度范围：–20°C 至 70°C
2.6mm × 1.6mm DSBGA 封装，0.5mm 间距
电源：Rx：2V 至 3.6V；Tx：3V 至 5.25V；
IO：1.8V 至 3.6V
简化框图
TX_SUP
RX_SUP
LDO
TX_SUP
TX1
TX2
TX3
Offset
Cancellation
DAC
I-V Amplifier (TIA)
Cf
LED
Driver
ILED
IO_SUP
I2C_CLK
I2C_DAT
RESETZ
Rf
Rf
Cf
Buffer
INP
INM
Noise-
Reduction
Filter
I2C Interface
IO
Buffer
ADC
Internal,
External
Clock
Timing
Engine
ADC_RDY
CLK
GND
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
English Data Sheet: SBAS689
AFE4404
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
www.ti.com.cn
目录
8.3 Feature Description................................................. 13
8.4 Device Functional Modes........................................ 28
8.5 Register Map........................................................... 32
Application and Implementation ........................ 67
9.1 Application Information............................................ 67
9.2 Typical Application .................................................. 67
1
2
3
4
5
6
7
特性.......................................................................... 1
应用.......................................................................... 1
说明.......................................................................... 1
修订历史记录 ........................................................... 2
Device Comparison Table..................................... 3
Pin Configuration and Functions......................... 3
Specifications......................................................... 5
7.1 Absolute Maximum Ratings ...................................... 5
7.2 ESD Ratings.............................................................. 5
7.3 Recommended Operating Conditions....................... 5
7.4 Thermal Information.................................................. 5
7.5 Electrical Characteristics........................................... 6
7.6 Timing Requirements ............................................... 7
7.7 Typical Characteristics.............................................. 8
Detailed Description ............................................ 12
8.1 Overview ................................................................. 12
8.2 Functional Block Diagram ....................................... 12
9
10 Power Supply Recommendations ..................... 74
11 Layout................................................................... 76
11.1 Layout Guidelines ................................................. 76
11.2 Layout Example .................................................... 76
12 器件和文档支持 ..................................................... 77
12.1 社区资源................................................................ 77
12.2 商标....................................................................... 77
12.3 静电放电警告......................................................... 77
12.4 Glossary................................................................ 77
13 机械、封装和可订购信息....................................... 78
8
4 修订历史记录
注：之前版本的页码可能与当前版本有所不同。
Changes from Revision B (October 2015) to Revision C
Page
•
•
•
•
•
Changed specifications of t1 and t4 rows in Table 7 to improve rejection of ambient light................................................... 23
Changed Description column in Table 10 ........................................................................................................................... 25
Changed Table 11 ................................................................................................................................................................ 26
Changed Table 12 ................................................................................................................................................................ 27
Added Reducing Sensitivity to Ambient Light Modulation section........................................................................................ 69
Changes from Revision A (August 2015) to Revision B
Page
•
•
•
•
•
•
•
•
Changed TX_SUP pin number to E3 in Pin Functions table ................................................................................................. 4
Added Figure 9 ....................................................................................................................................................................... 9
Added Decimation Mode section ......................................................................................................................................... 31
Added rows 3Dh, 3Fh, and 40h to Table 16 ........................................................................................................................ 34
Added Register 3Dh description to Register Map section.................................................................................................... 65
Added Register 3Fh and Register 40h descriptions to Register Map section...................................................................... 66
Added System-Level ESD Considerations section ............................................................................................................. 68
Added input-referred current paragraph associated to Figure 9 in Application Curves section........................................... 71
Changes from Original (June 2015) to Revision A
Page
•
•
•
•
•
Deleted Diagnostics Mode section ....................................................................................................................................... 30
Changed bit 2 of address 00h to 0 in Table 16 ................................................................................................................... 32
Deleted row 30h from Table 16 ........................................................................................................................................... 33
Changed bit 2 name and description in Register 0h ........................................................................................................... 35
Deleted Register 30h ........................................................................................................................................................... 58
2
Copyright © 2015–2016, Texas Instruments Incorporated
AFE4404
www.ti.com.cn
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
5 Device Comparison Table
LED DRIVE
CURRENT
(mA, Max)
OPERATING
TEMPERATURE
RANGE
LED DRIVE
CONFIGURATION
PRODUCT
PACKAGE-LEAD
OPTIMIZED APPLICATION
H-bridge,
common anode
AFE4400
AFE4490
VQFN-40
VQFN-40
50
0°C to 70°C
Finger-clip pulse oximeters
H-bridge,
common anode
200
–40°C to 85°C
Clinical-grade pulse oximeters
H-bridge,
common anode
AFE4403
AFE4404
DSBGA-36
DSBGA-15
100
–20°C to 70°C
–20°C to 70°C
Clinical pulse oximeter patches, wearables
Wearable optical bio-sensing
Common anode
50(1)
(1) Mode that doubles the range to 100 mA with additional restrictions.
6 Pin Configuration and Functions
YZP Package
15-Ball DSBGA
Bottom View
I2C_DAT
RESETZ
I2C_CLK
TX2
TX_SUP
E
D
C
B
A
GND
DNC
INP
CLK
TX3
TX1
ADC_RDY
INM
1
RX_SUP
IO_SUP
2
3
Copyright © 2015–2016, Texas Instruments Incorporated
3
AFE4404
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
www.ti.com.cn
Pin Functions
PIN
I/O
DESCRIPTION
NAME
NO.
ADC_RDY
B2
Digital
Digital
ADC ready interrupt signal (output)
Clock input or output, selectable based on register. Default is input (external clock mode).
Can be set via a register to output the clock when the oscillator is enabled.(1)(2)
CLK
C2
DNC
C1
D3
E2
E1
A1
B1
Do not connect (leave floating)
GND
Ground
Digital
Digital
Analog
Analog
Common ground for transmitter and receiver
I2C clock input, external pullup resistor to IO_SUP (for example, 10 kΩ)
I2C data, external pullup resistor to IO_SUP (for example, 10 kΩ)
Connect only to anode of photodiode(3)
I2C_CLK
I2C_DAT
INM
INP
Connect only to cathode of photodiode(3)
Separate supply for digital I/O. Must be less than or equal to RX_SUP.
Can be tied to RX_SUP.
IO_SUP
A3
Supply
RESETZ or PWDN: function based on (active low) duration of RESETZ pulse(4)
A 25-µs to 50-µs duration = RESETZ active.
.
RESETZ
D1
Digital
A > 200-µs duration = PWDN active.
RX_SUP
TX1
A2
B3
D2
C3
E3
Supply
Analog
Analog
Analog
Supply
Receiver supply; 1-µF decapacitor to GND
Transmit output, LED1
TX2
Transmit output, LED2
TX3
Transmit output, LED3
TX_SUP
Transmitter supply; 1-µF decapacitor to GND
(1) Depending on whether external clock mode or internal oscillator mode is used, extra series or shunt resistors are recommended on the
CLK pin. For more details, see the Typical Application section.
(2) In both hardware power-down (PWDN) and software power-down (PDNAFE) modes, the CLK pin is driven by the AFE to 0 V.
Therefore, if operating in external clock mode, take care to shut off the external clock to the AFE when in these power-down modes.
(3) Maintain the indicated polarity of photodiode connections to the AFE input pins.
(4) A RESET pulse must be applied after power-up to ensure that the registers are all reset to their default values.
4
Copyright © 2015–2016, Texas Instruments Incorporated
AFE4404
www.ti.com.cn
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
MIN
–0.3
–0.3
–0.3
–0.3
MAX
UNIT
RX_SUP to GND
4
4
IO_SUP to GND
Supply voltage range
V
RX_SUP-IO_SUP
TX_SUP to GND
6
Voltage applied to analog inputs
Voltage applied to digital inputs
Max [–0.3, (GND – 0.3)]
Max [–0.3, (GND – 0.3)]
Min [4, (RX_SUP + 0.3)]
Min [4, (IO_SUP + 0.3)]
V
V
50-mA LED current mode
(ILED_2X = 0)
10%
Maximum duty cycle (cumulative):
sum of all LED phase durations as a function
of the total period
100-mA LED current mode
(ILED_2X = 1)
3%
Storage temperature, Tstg
–60
150
°C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
7.2 ESD Ratings
VALUE
±1000
±250
UNIT
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)
Charged device model (CDM), per JEDEC specification JESD22-C101(2)
V(ESD)
Electrostatic discharge
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
MAX
3.6
UNIT
V
RX_SUP
IO_SUP
Receiver supply
2
Input/output supply
1.7
Min (3.6, RX_SUP)
V
(1)
50-mA LED current mode
(ILED_2X = 0)
3.0 or (0.5 + VLED
)
,
5.25
5.25
whichever is greater
TX_SUP
Transmitter supply
V
(1)
100-mA LED current mode
(ILED_2X = 1)
3.0 or (1.0 + VLED) ,
whichever is greater
Digital inputs
Analog inputs
0
0
IO_SUP
RX_SUP
70
V
V
Operating temperature range
–20
°C
(1) VLED refers to the maximum voltage drop across the external LED (at maximum LED current). This value is usually governed by the
forward drop voltage (VFB) of the LED.
7.4 Thermal Information
AFE4404
THERMAL METRIC(1)
YZP (DSBGA)
UNIT
15 BALLS
67.5
0.5
RθJA
Junction-to-ambient thermal resistance
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
RθJC(top)
RθJB
Junction-to-case (top) thermal resistance
Junction-to-board thermal resistance
12.9
0.2
ψJT
Junction-to-top characterization parameter
Junction-to-board characterization parameter
Junction-to-case (bottom) thermal resistance
ψJB
12.9
n/a
RθJC(bot)
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
Copyright © 2015–2016, Texas Instruments Incorporated
5
AFE4404
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
www.ti.com.cn
7.5 Electrical Characteristics
Minimum and maximum specifications are at TA = –20°C to 70°C, typical specifications are at 25°C. TX_SUP = 4 V, RX_SUP
= IO_SUP = 3 V, 100-Hz PRF, 8-MHz external clock (with CLKDIV_EXTMODE set to divide-by-2), detector CIN = 50 pF, and
CLKDIV_PRF set to 1, unless otherwise noted.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
PULSE REPETITION FREQUENCY
PRF(1)
Pulse repetition frequency
10(2)
1000
SPS
RECEIVER
Offset cancellation DAC current range
Offset cancellation DAC current step
TIA gain setting
–7 to 7
µA
µA
Ω
0.47
10k to 2M
2.5 to 25
2.5(3)
Cf setting
pF
kHz
Switched RC filter bandwidth
ADC averages
1
16
Detector capacitance
Differential capacitance between INP, INN
10
200
pF
TRANSMITTER
ILED_2X = 0
ILED_2X = 1
0 to 50
0 to 100
6
LED current range
mA
LED current resolution
CLOCKING (Internal Oscillator)
Frequency
Bits
4
±1%
MHz
Accuracy
Room temperature
Frequency drift with temperature
Full temperature range
±0.5%
100
Jitter (RMS)
ps
V
Output clock high level
Output clock low level
IO_SUP
0
V
10% to 90%, 15-pF load capacitance on
CLK pin
Output clock rise and fall times
< 30
ns
CLOCKING (External Clock)
Frequency range(4)
4
60
MHz
V
Input clock high level
Input clock low level
IO_SUP
0
V
Input capacitance of CLK pin
Capacitance to ground
< 4
pF
I2C INTERFACE
Maximum clock speed
I2C slave address
400
58
kHz
Hex
PERFORMANCE
SNR over a 20-Hz bandwidth for a 500-kΩ
gain setting, 50% FS output, 2% LED and
sampling pulse duration,
Receiver SNR
100
100
dBFS(5)
dBFS(5)
ADC averages set to 16
SNR over a 20-Hz bandwidth for a 50-mA
LED current setting
Transmitter SNR
(1) PRF refers to the rate at which samples from each of the four phases are output from the AFE.
(2) To extend the lower range of PRF down to 10 Hz, program the CLKDIV_PRF setting.
(3) The effective bandwidth of the switched RC filter scales as a function of the sampling duty cycle. For example, at 2% sampling width
duty cycle, the effective bandwidth of the switched RC filter is approximately 50 Hz.
(4) With appropriate setting of the clock divider ratio (CLKDIV_EXTMODE).
(5) dBFS refers to a full-scale voltage of 2 V.
6
Copyright © 2015–2016, Texas Instruments Incorporated
AFE4404
www.ti.com.cn
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
Electrical Characteristics (continued)
Minimum and maximum specifications are at TA = –20°C to 70°C, typical specifications are at 25°C. TX_SUP = 4 V, RX_SUP
= IO_SUP = 3 V, 100-Hz PRF, 8-MHz external clock (with CLKDIV_EXTMODE set to divide-by-2), detector CIN = 50 pF, and
CLKDIV_PRF set to 1, unless otherwise noted.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CURRENT CONSUMPTION
Normal operation, external clock mode
Normal operation, internal oscillator mode
In dynamic power-down mode(6)
Hardware power-down (PWDN) mode(7)
Software power-down (PDNAFE) mode(7)
Normal operation, external clock mode
Normal operation, internal oscillator mode
In dynamic power-down mode(6)
Hardware power-down (PWDN) mode(7)
Software power-down (PDNAFE) mode(7)
Normal operation, external clock mode(8)
Normal operation, internal oscillator mode(8)
In dynamic power-down mode(6)(8)
620
670
300
3
RX_SUP current
IO_SUP current
TX_SUP current
µA
35
20
5
20
3
µA
µA
5
25
25
5
Hardware power-down (PWDN) mode(7)(8)
Software power-down (PDNAFE) mode(7)(8)
2
2
TRANSIENT RECOVERY
tACTIVE
Recovery from PWDN mode
Time for signal chain to be functional(9)
10
ms
ms
Recovery from any event causing a
change in signal characteristics
PRF = 100 Hz, sampling duty cycle
(each phase) of 2%(10)
tCHANNEL
200
DIGITAL INPUTS
0.9 ×
IO_SUP
VIH
VIL
High-level input voltage
Low-level input voltage
IO_SUP
0
V
V
0.1 ×
IO_SUP
DIGITAL OUTPUTS
VOH
VOL
High-level output voltage
Low-level output voltage
IO_SUP
0
V
V
(6) In dynamic power-down mode for 90% and active mode for 10% of the period.
(7) External clock mode with the external clock switched off.
(8) LED currents set to 0 mA.
(9) For full performance to be restored, a longer time as governed by tCHANNEL can be applicable.
(10) tCHANNELscales inversely with the sampling duty cycle.
7.6 Timing Requirements
MIN
TYP
MAX
UNIT
I2C data rise time with a 10-kΩ pullup resistor with a 20-pF load from I2C
data to GND
tI2C_RISE
1200
ns
I2C data fall time (when the data line is pulled down by the AFE) with a 20-pF
load from I2C data to GND
tI2C_FALL
28
ns
tADC_RDY_RISE
tADC_RDY_FALL
ADC_RDY rise time (10% to 90%) with a 15-pF capacitive load to ground
ADC_RDY fall time (90% to 10%) with a 15-pF capacitive load to ground
21
21
ns
ns
Copyright © 2015–2016, Texas Instruments Incorporated
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AFE4404
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
www.ti.com.cn
7.7 Typical Characteristics
At 25°C, TX_SUP = 4 V, RX_SUP = IO_SUP = 3.3 V, 100-Hz PRF, 25% duty cycle, Rf = 500 kΩ, Cf is adjusted to keep the
TIA time constant at 1/10th of the sampling duration, 8-MHz external clock (with CLKDIV_EXTMODE set to divide-by-2),
CLKDIV_PRF = 1, detector CIN = 50 pF, ADC averaging = max allowed, SNR (dBFS) = noise referred to full-scale range of
2 V, noise integrated from 1 Hz to Nyquist (= PRF / 2), and values assigned to CLKDIV_EXTMODE and CLK_DIV_PRF
parameters correspond to division ratios controlled by these modes, unless otherwise specified.
1250
1150
1050
950
900
800
700
600
500
400
300
200
100
CLKDIV_EXTMODE = 1
CLKDIV_EXTMODE = 2
CLKDIV_EXTMODE = 3
CLKDIV_EXTMODE = 4
CLKDIV_EXTMODE = 6
CLKDIV_EXTMODE = 8
CLKDIV_EXTMODE = 12
CLKDIV_PRF = 1
CLKDIV_PRF = 16
850
750
650
550
0
10
20
30
40
50
60
0
200
400
600
800
1000
1200
1400
External Clock Frequency (MHz)
PRF (Hz)
Active window = 500 µs, LED pulse = 100 µs,
all four DYNAMIC bits set to 1
Figure 2. Receiver Current vs PRF in
Dynamic Power-Down Mode
Figure 1. Receiver Current vs External Clock Frequency
40
106
Output Voltage = 0% of FS
Output Voltage = 10% of FS
Output Voltage = 25% of FS
Output Voltage = 50% of FS
Output Voltage = 75% of FS
Output Voltage = 0% of FS
Output Voltage = 10% of FS
Output Voltage = 25% of FS
Output Voltage = 50% of FS
Output Voltage = 75% of FS
35
30
25
20
15
10
104
102
100
98
96
0
5
10
15
20
25
0
5
10
15
20
25
Duty Cycle (%)
Duty Cycle (%)
Duty cycle (x-axis) refers to the sampling duration expressed as a
percentage of the pulse repetition period.
Duty cycle (x-axis) refers to the sampling duration expressed as a
percentage of the pulse repetition period.
Figure 3. Input-Referred Noise Current in 20-Hz Bandwidth
vs Duty Cycle for Different Output Levels
(As a Percentage of Full-Scale)
Figure 4. Signal-to-Noise Ratio in 20-Hz Bandwidth vs Duty
Cycle for Different Output Levels
(As a Percentage of Full-Scale)
108
100000
50000
Rf = 10 kW
Rf = 25 kW
Rf = 50 kW
Rf = 100 kW
Rf = 250 kW
Rf = 500 kW
Rf = 1000 kW
Rf = 2000 kW
Rf = 10 kW
Rf = 25 kW
Rf = 50 kW
Rf = 100 kW
Rf = 250 kW
Rf = 500 kW
Rf = 1000 kW
Rf = 2000 kW
20000
10000
5000
106
104
102
100
98
2000
1000
500
200
100
50
20
10
5
2
1
0
5
10
15
20
25
0
5
10
15
20
25
Duty Cycle (%)
Duty Cycle (%)
Figure 5. Receiver Input-Referred Noise Current in 20-Hz
BW vs Duty Cycle (Different TIA Gain Settings)
Figure 6. Receiver SNR in 20-Hz BW vs Duty Cycle
(Different TIA Gain Settings)
8
Copyright © 2015–2016, Texas Instruments Incorporated
AFE4404
www.ti.com.cn
ZHCSDV4C –JUNE 2015–REVISED MAY 2016
Typical Characteristics (continued)
At 25°C, TX_SUP = 4 V, RX_SUP = IO_SUP = 3.3 V, 100-Hz PRF, 25% duty cycle, Rf = 500 kΩ, Cf is adjusted to keep the
TIA time constant at 1/10th of the sampling duration, 8-MHz external clock (with CLKDIV_EXTMODE set to divide-by-2),
CLKDIV_PRF = 1, detector CIN = 50 pF, ADC averaging = max allowed, SNR (dBFS) = noise referred to full-scale range of
2 V, noise integrated from 1 Hz to Nyquist (= PRF / 2), and values assigned to CLKDIV_EXTMODE and CLK_DIV_PRF
parameters correspond to division ratios controlled by these modes, unless otherwise specified.
50
45
40
35
30
25
20
102
100
98
ADC Averaging = 1
ADC Averaging = 2
ADC Averaging = 4
ADC Averaging = 8
ADC Averaging = 16
ADC Averaging = 1
ADC Averaging = 2
ADC Averaging = 4
ADC Averaging = 8
ADC Averaging = 16
96
94
0
5
10
15
20
25
0
5
10
15
20
25
Duty Cycle (%)
Duty Cycle (%)
Figure 7. Receiver Input-Referred Noise Current over
Nyquist Bandwidth vs Duty Cycle (Different ADC Averaging)
Figure 8. Receiver Signal-to-Noise Ratio over Nyquist
Bandwidth vs Duty Cycle (Different ADC Averaging)
500
220
I_OFFDAC = 0 mA, Rf = 25 kW
I_OFFDAC = 7 mA, Rf = 1000 kW
I_OFFDAC = 7 mA, Rf = 250 kW
Decimation Factor = 1
Decimation Factor = 2
Decimation Factor = 4
Decimation Factor = 8
Decimation Factor = 16
400
180
300
200
100
0
140
100
60
20
0
5
10
15
20
25
0
5
10
15
20
25
Duty Cycle (%)
Duty Cycle (%)
D022
Figure 10. Receiver Input-Referred Noise in 20-Hz
Bandwidth vs Duty Cycle
(Different Offset Cancellation DAC Currents)
Figure 9. Input-Referred Noise Current in Nyquist
Bandwidth vs Duty Cycle (Different Decimation Factor)
8
10
5% Duty Cycle
25% Duty Cycle
4
0
-10
-20
-30
-40
-50
0
-4
-8
PRF = 50 Hz
PRF = 100 Hz
PRF = 200 Hz
PRF = 400 Hz
PRF = 800 Hz
PRF = 1000 Hz
-12
-16
-20
1
2
3 4 567 10
20 30 50 70100 200
Frequency (Hz)
500 1000
0
100 200 300 400 500 600 700 800 900 1000
Frequency (Hz)
PRF = 2000 Hz
Figure 11. Response of the Switched-RC Filter
at the AFE Output
Figure 12. Filter Response for Multiple PRFs at
1% Duty Cycle
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Typical Characteristics (continued)
At 25°C, TX_SUP = 4 V, RX_SUP = IO_SUP = 3.3 V, 100-Hz PRF, 25% duty cycle, Rf = 500 kΩ, Cf is adjusted to keep the
TIA time constant at 1/10th of the sampling duration, 8-MHz external clock (with CLKDIV_EXTMODE set to divide-by-2),
CLKDIV_PRF = 1, detector CIN = 50 pF, ADC averaging = max allowed, SNR (dBFS) = noise referred to full-scale range of
2 V, noise integrated from 1 Hz to Nyquist (= PRF / 2), and values assigned to CLKDIV_EXTMODE and CLK_DIV_PRF
parameters correspond to division ratios controlled by these modes, unless otherwise specified.
5
120
100
80
60
40
20
0
50-mA LED Current Mode
100-mA LED Current Mode
0
-5
-10
-15
-20
-25
-30
PRF = 50 Hz
PRF = 100 Hz
PRF = 200 Hz
PRF = 400 Hz
PRF = 800 Hz
PRF = 1000 Hz
0
100 200 300 400 500 600 700 800 900 1000
Frequency (Hz)
0
10
20
30
40
50
60
Transmitter DAC Current Setting Code
Figure 13. Filter Response for Multiple PRFs at
5% Duty Cycle
Figure 14. Transmitter Current Linearity
60
40
20
0
120
100
80
50-mA LED Current Mode
100-mA LED Current Mode
60
-20
-40
-60
40
20
0.3
0.9
1.5
2.1
2.7
3.3
0
10
20
30
40
50
60
Transmitter Head_Room Voltage (V)
Transmitter DAC Current Setting Code
Figure 15. LED Current vs Transmitter Headroom Voltage
Figure 16. Transmitter DAC Current Step Error in
50-mA Mode
100
90
80
70
60
50
40
100
75
50
25
0
-25
-50
-75
-100
0
10
20
30
40
50
60
10
100
1000
10000
100000
1000000
Transmitter DAC Current Setting Code
Frequency (Hz) of Tone at TX_SUP Pin
Duty cycle = 1%
Figure 17. Transmitter DAC Current Step Error in
100-mA Mode
Figure 18. PSRR vs Tone Frequency at TX_SUP
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Typical Characteristics (continued)
At 25°C, TX_SUP = 4 V, RX_SUP = IO_SUP = 3.3 V, 100-Hz PRF, 25% duty cycle, Rf = 500 kΩ, Cf is adjusted to keep the
TIA time constant at 1/10th of the sampling duration, 8-MHz external clock (with CLKDIV_EXTMODE set to divide-by-2),
CLKDIV_PRF = 1, detector CIN = 50 pF, ADC averaging = max allowed, SNR (dBFS) = noise referred to full-scale range of
2 V, noise integrated from 1 Hz to Nyquist (= PRF / 2), and values assigned to CLKDIV_EXTMODE and CLK_DIV_PRF
parameters correspond to division ratios controlled by these modes, unless otherwise specified.
120
100
80
60
40
20
0
50
40
30
20
10
0
LED Data
(LED - AMB) Data
10
100
1000
10000
100000
1000000
0
1000
2000
3000
4000
5000
Frequency (Hz) of Tone at RX_SUP Pin
Spacing between LED and AMB Sampling Instants (ms)
Duty cycle = 1%
PRF = 200 Hz, NUMAV = 0
Figure 19. PSRR vs Tone Frequency at RX_SUP
Figure 20. Rejection of a 50-Hz Differential Tone Across
Spacing Between LED and Ambient Phases
108
4.06
4.04
4.02
4
Temperature = -40è C
Temperature = 27è C
Temperature = 85è C
106
104
102
100
98
3.98
3.96
0
5
10
15
20
25
-40
-20
0
20
40
60
80
100
Duty Cycle (%)
Temperature (è C)
Figure 21. Receiver SNR in a 20-Hz Bandwidth vs
Duty Cycle Across Different Temperatures
Figure 22. Internal Oscillator Frequency vs
Temperature on a Typical Unit
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8 Detailed Description
8.1 Overview
The AFE has an integrated transmitter and receiver for optical heart-rate monitoring and pulse oximetry
applications. The system is characterized by a parameter termed the pulse repetition frequency (PRF) that
determines the repetition periodicity of a sequence of operations. Every cycle of a PRF results in four 24-bit
digital samples at the output of the AFE, each of which is stored in a separate register.
8.2 Functional Block Diagram
TX_SUP
RX_SUP
TX_SUP
TX2
TX3
TX1
LDO
Offset
Cancellation DAC
ILED
6-Bit LED
Current Control
I-V Amplifier (TIA)
Cf
CONVLED2
SLED2
LED2
Filter
Rf
Filter
Buffer
INP
INM
LED2 Ambient, LED3
Analog-to-Digital
Converter
CONVLED2_amb
SLED2_amb
SLED1
IO_SUP
CONVLED1
LED1
Filter
Rf
I2C_CLK
I2C_DAT
RESET
Filter
I2C Interface
Cf
LED1 Ambient
SLED1_amb
CONVLED1_amb
IO
Buffer
OSC_ENABLE
4-MHz
Oscillator
1
0
4-MHz Clock
CLK
Timing
Engine
ADC_RDY
GND
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8.3 Feature Description
8.3.1 TIA and Switched RC Filter
The receiver input pins (INP, INM) are meant to be connected differentially to a photodiode. The signal current
from the photodiode is converted to a differential voltage using a transimpedance amplifier (TIA). The TIA gain is
set by its feedback resistor (Rf) and can be programmed from 10 kΩ to 2 MΩ. The transimpedance gain between
the input current and output differential voltage of the TIA is equal to 2 × Rf. At the output of the TIA is a switched
RC filter. There are four parallel instances of the filter, each of which are connected to the TIA output signal
during one of four sampling phases.
The signal chain is kept fully differential throughout the receiver channel in order to enable excellent rejection of
common-mode noise as well as noise on power supplies. For simplicity, the scheme with the four parallel filters
is shown in Figure 23 for a single-ended representation of the signal chain. The ADCRST signal corresponds to
the collection of active phases of four ADCRST pulses: ADCRST0, ADCRST1, ADCRST2, and ADCRST3.
SLED2
CONVLED2
Cf
CSAMP1
CONVLED2_AMB,
CONVLED3
SLED2_AMB, SLED3
Rf
CSAMP2
Analog-to-Digital
Converter
Buffer
CBUF
SLED1
CONVLED1
ADCRST(1)
Transimpedance Amplifier
CSAMP3
SLED_AMB
CONVLED_AMB
CSAMP4
Switched RC Filter
NOTE: For simplicity, this circuit is shown in single-ended format.
(1) ADCRST corresponds to ADCRST0, ADCRST1, ADCRST2, or ADCRST3.
Figure 23. Four Sampling and Conversion Phases Diagram
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Feature Description (continued)
8.3.1.1 Operation with Two and Three LEDs
The four sampling phases can correspond to either of the following signal state sequences received by the
photodiode:
1. 2-LED mode: LED2 → ambient phase 2 → LED1 → ambient phase 1
2. 3-LED mode: LED2 → LED3 → LED1 → ambient
The sequence of the phases within a pulse repetition cycle is shown in Figure 24.
Pulse Repetition Period
Rf2, Cf2
Sample LED2
Sample Ambient 2 or LED3
Rf1, Cf1
Sample LED1
Sample Ambient 1
Convert LED2
Convert Ambient 2 or LED3
Convert LED1
Convert Ambient 1
PDN_CYCLE
ADC_RDY
Figure 24. Sequence of Four Sampling and Conversion Phases
In the 2-LED mode, LED1 and LED2 are pulsed during the corresponding sampling instants. In the 3-LED mode,
LED1, LED2, and LED3 are pulsed during the corresponding sampling instants. As mentioned in the TIA Gain
Settings and Operation with Two and Three LEDs sections, the TIA gain (Rf) and feedback capacitor (Cf) can be
programmed differently between two sets: Rf1 / Cf1 and Rf2 / Cf2. The way these sets are applied to the four
phases is shown in Figure 24.
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Feature Description (continued)
8.3.1.1.1 LED Current Setting
The default LED current range is from 0 mA to 50 mA. The individual currents of each of the three LEDs can be
controlled independently, each with a separate 6-bit control.
Taken as a decimal number, the 6-bit setting provides 63 equal steps between 0 mA and 50 mA. Each increment
of the ILED 6-bit code causes the LED current setting to increment by approximately 0.8 mA. For details, see
register 22h.
The LED current range can be doubled by setting the ILED_2X bit to 1. The accuracy of higher current settings
close to 100 mA can be low because of current saturation of the driver. Each increment of the ILED 6-bit code
causes the LED current to increment by approximately 1.6 mA when ILED_2X is set to 1.
8.3.1.2 TIA Gain Settings
The TIA gain is set by programming the value of Rf (the feedback resistor of the TIA). The Rf setting is controlled
using the TIA_GAIN register bit. For details see register 21h.
By default, the same TIA_GAIN setting is applied for all four phases of the receiver. Separate gains can be set
for two of the four phases by setting the EN_SEP_GAIN bit. When the EN_SEP_GAIN bit is enabled, the
TIA_GAIN register controls the Rf1 setting and the TIA_GAIN_SEP register controls the Rf2 settings.
Mapping of the Rf1 / Rf2 values to the two sets of 3-bit controls is described in Table 50.
8.3.1.3 TIA Bandwidth Settings
TIA bandwidth settings are similar to TIA gain settings. The TIA bandwidth is set by programming the value of Cf
(the feedback capacitance of the TIA). The product of Rf and Cf gives the time constant of the TIA and must be
set approximately 1/5th (or less) of the LED or sampling pulse durations. This choice of time constant allows the
TIA to pass the incoming pulses from the photodiode.
Cf is controlled using the TIA_CF register bit. For details, see register 21.
By default, the same TIA_CF setting is applied for all four phases of the receiver. Similar to the TIA gain settings,
a separate Cf can be set for two of the four phases by setting the EN_SEP_GAIN bit. When the EN_SEP_GAIN
bit is enabled, the TIA_CF register controls the Cf1 settings and TIA_CF_SEP controls the Cf2 settings. Mapping
the Cf1 / Cf2 values to the two sets of 3-bit controls is the same as illustrated in Table 51.
8.3.2 Power Management
The AFE has three independent supplies for the transmitter, receiver, and I/O.
8.3.2.1 Transmitter Supply (TX_SUP)
The transmitter supply has a range of 3.0 V to 5.25 V. In the most common arrangement, this supply can be the
same supply that the anodes of the LEDs are tied to, as shown in Figure 25.
TX_SUP
LEDs
TX_SUP
TX1
TX2
TX3
AFE
Figure 25. LED to Pin Connections
When the LEDs must be tied to a different supply, care must be taken to ensure that the LED supply is within
0.3 V of TX_SUP. This consideration of the LED supply voltage prevents the electrostatic discharge (ESD)
diodes inside the AFE from turning on during the off state of the LEDs.
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Feature Description (continued)
8.3.2.2 Receiver Supply (RX_SUP)
The receiver supply has a range of 2.0 V to 3.6 V. The AFE has internal low-dropout (LDO) regulators operating
at 1.8 V that regulate both the analog and digital blocks inside the AFE. This rejection of supply noise from the
internal LDOs, coupled with the differential nature of the architecture, enables excellent noise rejection on the
supplies (for instance, 50-Hz noise).
8.3.2.3 I/O Supply (IO_SUP)
The I/O supply can either be tied to RX_SUP or can be separately driven. The motivation for a separate I/O
supply is to interface with certain microcontrollers (MCUs) that require a 1.8-V I/O current. In this case, IO_SUP
can be driven separately from RX_SUP and can be tied to 1.8 V.
8.3.2.4 Boost Converters Selection
If the supply voltage for TX_SUP (and the LEDs) is unavailable in the system, a boost converter may be required
to generate the supply voltage. TI has a portfolio of boost converters from which an appropriate device can be
selected. Some choices are listed in Table 1.
Table 1. TI Boost Converter Details(1)
TYPICAL
QUIESCENT
CURRENT (µA)
SIZE
(mm, L × W × H)
INPUT SUPPLY
(V)
TI PART NUMBER
OUTPUT SUPPLY
EXTERNAL COMPONENTS
Different parts with a
fixed voltage up to 5 V
TPS61254
1.2 × 1.3 × 0.625
2.3 to 5.5
36
2 capacitors, 1 inductor
TPS61240
TPS61252
TPS61220
0.9 × 1.3 × 0.625
2 × 2 × 0.75
2.3 to 5.5
2.3 to 6
5 V (fixed)
30
30
2 capacitors, 1 inductor
Adjustable up to 6.5 V
Adjustable from 1.8 V to 6 V
3 capacitors, 1 inductor, 4 resistors
2 capacitors, 1 inductor, 2 resistors
2 × 2.2 × 1
0.7 to 5.5
5.5
(1) For the most current information, see the TI data sheets corresponding to each device (available for download from www.ti.com).
8.3.3 Offset Cancellation DAC
A typical optical heart-rate signal has a dc component and an ac component. Although a higher TIA gain
maximizes the ac signal at the AFE output, the magnitude of the dc component limits the maximum gain possible
in the TIA. In order to decouple the affect of the dc level on the allowed ac signal gain, a current digital-to-analog
converter (DAC) is placed at the input of the device. By setting a programmable cancellation current (based on
the dc current signal level), the effective signal that is gained up by the TIA can be reduced. This reduction in the
effective signal current into the TIA results in the ability to set a higher TIA gain than what is otherwise possible
without enabling the offset correction. In each of the four phases of operation, a separate programmable current
value can be set by programming four different sets of register bits. These cancellation currents are automatically
presented to the input of the TIA in the appropriate phase. The ability to set a different cancellation current in
each of the four phases can be used to cancel out the ambient current in the ambient phase. In the LED on
phase, this ability can be used to cancel out the sum of the ambient current and dc current of the heart-rate
signal. The polarities of the signal current and offset cancellation current is illustrated in Figure 26. The polarity of
the offset cancellation current can be reversed by programming the POL_OFFDAC bits.
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With zero input current and zero current in the offset cancellation DAC, the output of the AFE will be close to
zero. Based on the channel offset, the output voltage for zero input current could be a small positive or negative
value, usually in the range of several mV. With the photodiode connected as shown in Figure 26 and a signal
current coming from the photodiode, the output code of the device is expected to be positive with the offset
cancellation DAC set to zero (Ioffset = 0). With Ioffset set negative (POL_OFFFAC = 1), a dc offset can be
subtracted from the signal and the ac signal can be amplified with a higher gain than what is otherwise possible.
Cf
IPD
Ioffset
Rf
+
INP
INM
PD
TIA_diff
_
Cf
Ioffset
IPD
Rf
Figure 26. Offset Cancellation Current Polarity Diagram
A breakdown of the signal current and voltage levels is provided in Table 2 for a variety of signal levels. In
Table 2, the current transfer ratio (CTR) is used to describe the relationship between the set LED current and the
resulting photodiode current (IPD). CTR is the ratio of the photodiode current for a given LED current and is a
function of the optical and mechanical parameters as well as human physiology.
Table 2. Signal Current and Voltage Levels for a Hypothetical Use Case(1)
CTR
(µA / mA)
I_OFFDAC
(µA)
PHASE
ILED (mA)
Isig (µA)
Iamb (µA)
IPD (µA)
Ieff (µA)
Rf (MΩ)
TIA_diff (V)
LED2
LED3
LED1
AMB1
25
50
0.025
0.025
0.025
0.025
0.625
1.25
0.3125
0
1
1
1
1
1.625
2.25
1.3125
1
–1.4
–1.87
–0.93
–0.93
0.225
0.38
1
0.45
0.38
0.5
0.5
2
12.5
0
0.3825
0.07
0.3825
0.28
(1) ILED is the set LED current; CTR is the current transfer ratio (in µA / mA); Isig is the photodiode signal current resulting from LED
pulsing (Isig = ILED × CTR); Iamb is the current in the photodiode resulting from ambient light (that is present in all phases and adds to
Isig); IPD is the total input current (Isig + Iamb); I_OFFDAC is the current setting of the offset cancellation DAC; Ieff is the effective current
after offset cancellation (Isig + I_OFFDAC); Rf is the TIA gain setting; and TIA_diff is the output differential signal of the TIA (note that
this signal must be within the range of ±1 V).
8.3.3.1 Offset Cancellation DAC Controls
The I_OFFDAC bits control the magnitude of the current subtracted (or added) at the TIA input. The
POL_OFFDAC bits control the polarity of the current and determine whether the current is subtracted from or
added to the input. For details, see register 3Ah.
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8.3.4 Analog-to-Digital Converter (ADC)
The AFE has an ADC that provides a 22-bit representation of the current from the photodiode. The ADC codes
corresponding to the various sampling phases can be read out from 24-bit registers in twos complement format.
The ADC full-scale input range is ±1.2 V and spans bits 21 to 0. The mapping of the ADC input voltage to the
ADC code is shown in Table 3.
Table 3. Mapping the ADC Input Voltage to the ADC Code
DIFFERENTIAL INPUT VOLTAGE AT ADC INPUT
24-BIT ADC OUTPUT CODE
111000000000000000000000
111111111111111111111111
000000000000000000000000
000000000000000000000001
000111111111111111111111
–1.2 V
(–1.2 / 221) V
0
(1.2 / 221) V
1.2 V
The two MSBs of the 24-bit word serve as sign-extension bits to the 22-bit ADC code and are equal to the MSB
of the 22-bit ADC code when the input to the ADC is within its full-scale range, as shown in Table 4.
Table 4. Using Sign-Extension Bits to Determine the Input Operating Voltage
BITS 23-21
000
INPUT STATUS
Positive and lower than positive full-scale (within full-scale range)
Negative and higher than negative full-scale (within full-scale range)
Positive and higher than positive full-scale (outside full-scale range)
Negative and lower than negative full-scale (outside full-scale range)
111
001
110
Noted that the TIA has an operating range of ±1 V even though the ADC input full-scale range is ±1.2 V, as
shown in Figure 27. When setting the TIA gain, ensure that the signal at the TIA output does not exceed ±1 V.
ADC Max
(Differential)
1.2 V
TIA Max
(Differential)
1 V
0 V
TIA Min
(Differential)
-1 V
ADC Min
(Differential)
-1.2 V
Figure 27. TIA and ADC Dynamic Ranges
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8.3.5 I2C Interface
The AFE has an I2C interface for communication. The I2C_CLK and I2C_DAT lines require external pullup
resistors to IO_SUP. See the I2C protocol standards documents for details of the I2C interface. This section only
describes certain key features of the interface. The data on I2C_DAT must be stable during the high level of
I2C_CLK and may transition during the low level of I2C_CLK, as shown in Figure 28.
Data Line
Data Line
Stable Data
Transition
Allowed
I2C_DAT
I2C_CLK
Figure 28. Allowed Transition of I2C_DAT while Transmission of Data Bits
The start condition is indicated by a high-to-low transition of the I2C_DAT line when the I2C_CLK is high. A stop
condition is indicated by a low-to-high transition of the I2C_DAT line when the I2C_CLK is high. Figure 29 shows
the start and stop conditions.
I2C_DAT
I2C_CLK
STOP
Condition (P)
START
Condition (S)
Figure 29. Transition of I2C_DAT during Start and Stop Conditions
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With the previously mentioned protocols for data, start, and stop conditions in place, the write and read
operations are as shown in Figure 30 and Figure 31, respectively. In Figure 30 and Figure 31, the slave address
for the AFE (indicated as SA6 to SA0) is a 7-bit representation of address 58h. The R/W bit is the read/write bit
and is set to '1' for Read and '0' for Write. Only the ADC output registers (addressed from 2Ah to 2Fh) can be
read out without the need for setting the REG_READ bit. Prior to reading out any other register, the REG_READ
bit needs to be additionally set to '1'. In Figure 30 and Figure 31, the activity performed by the host is shown in
black whereas activity from the AFE is shown in red. Thus, after the host sends the slave address during a write
operation, the AFE pulls the I2C_DAT line low (shown as ACK) if the slave address matches 58h. Similarly, the
host pulls the I2C_DAT line high (shown as NACK) as acknowledgment of a successfully completed read
operation involving three bytes of data. Continuous read/write mode is not supported.
S
P
ACK
ACK
ACK
ACK
R/W
I2C_DAT
ACK
SA5 SA4
SA2 SA1 SA0
A6
A5
A3
A2
A1
A0
DATA[23:16]
DATA[7:0]
SA6
SA3
A7
A4
DATA[15:8]
Slave Address
Register Address
(1) Activity performed by the host is shown in black whereas activity from the AFE is shown in red. Continuous read/write
mode is not supported.
Figure 30. I2C Write Option Timing
S
P
S
ACK
SLAVE ADDRESS
REG ADDRESS
SLAVE ADDRESS
R/W
ACK
ACK
DATA[23:16]
DATA[15:8]
DATA[7:0]
ACK
ACK
R/W
NACK
I2C_DAT
Figure 31. I2C Read Option Timing
8.3.6 Timing Engine
The AFE has a fully-integrated timing engine that can be programmed to generate all clock phases for
synchronized transmit drive, receive sampling, and data conversion. To enable the timing engine (after powering
up the device), enable the TIMEREN bit.
8.3.6.1 Timer and PRF Controls
The timing engine inside the AFE has a 16-bit counter. The duration of the count with respect to an internal clock
(the timer clock) determines the pulse repetition period. The pulse repetition frequency (PRF) can be set using
the PRPCT register bits that represent the high value of the counter (the low value of the counter is 0). The
counter automatically counts until reaching PRPCT and then returns to 0 to start the next count. To suspend the
count and keep the counter in reset state, enable the TM_COUNT_RST bit.
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8.3.6.2 Timing Control Registers
The start and stop counts for the various dynamic signals generated by the timing engine are shown in Table 5.
The timing edge numbers are in reference to Figure 32.
Table 5. Timing Register and Edge Details
REGISTER
ADDRESS (Hex)
TIMING SIGNAL
DESCRIPTION
TIMING EDGE
LED2STC
LED2ENDC
Sample LED2 start
Sample LED2 end
1h
2h
TE3
TE4
LED1LEDSTC
LED1 start
3h
TE17
TE18
TE11
TE12
TE19
TE20
TE1
LED1LEDENDC
ALED2STC\LED3STC
ALED2ENDC\LED3ENDC
LED1STC
LED1 end
4h
Sample ambient 2 (or sample LED3) start
Sample ambient 2 (or sample LED3) end
Sample LED1 start
5h
6h
7h
LED1ENDC
Sample LED1 end
8h
LED2LEDSTC
LED2 start
9h
LED2LEDENDC
ALED1STC
LED2 end
Ah
TE2
Sample ambient 1 start
Sample ambient 1 end
LED2 convert phase start
LED2 convert phase end
Ambient 2 (or LED3) convert phase start
Ambient 2 (or LED3) convert phase end
LED1 convert phase start
LED1 convert phase end
Ambient 1 convert phase start
Ambient 1 convert phase end
ADC reset phase 0 start
ADC reset phase 0 end
ADC reset phase 1 start
ADC reset phase 1 end
ADC reset phase 2 start
ADC reset phase 2 end
ADC reset phase 3 start
ADC reset phase 3 end
Bh
TE25
TE26
TE7
ALED1ENDC
Ch
LED2CONVST
Dh
LED2CONVEND
ALED2CONVST\LED3CONVST
ALED2CONVEND\LED3CONVEND
LED1CONVST
Eh
TE8
Fh
TE15
TE16
TE23
TE24
TE29
TE30
TE5
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
LED1CONVEND
ALED1CONVST
ALED1CONVEND
ADCRSTSTCT0
ADCRSTENDCT0
ADCRSTSTCT1
ADCRSTENDCT1
ADCRSTSTCT2
ADCRSTENDCT2
ADCRSTSTCT3
ADCRSTENDCT3
TE6
TE13
TE14
TE21
TE22
TE27
TE28
When three LEDs are used within a single period, the Ambient2 phase is replaced by the LED3 phase. The
timing controls for driving the third LED are as shown in Table 6.
Table 6. Timing Controls for Driving the Third LED
TIMING SIGNAL
LED3LEDSTC
DESCRIPTION
LED3 start
REGISTER ADDRESS (Hex)
TIMING EDGE
TE9
36h
37h
LED3LEDENDC
LED3 end
TE10
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The timing diagram for when all three LEDs are active is shown in Figure 32.
Count = 0
Count = PRPCT
LED2
TE1
TE2
TE4
SLED2
TE3
ADCRST0
TE5
TE6
CONVLED2
TE7
TE8
LED3
TE9
TE10
SLED3
TE11
TE12
ADCRST1
TE13
TE14
CONVLED3
TE15
TE16
TE18
LED1
TE17
SLED1
TE19
TE20
ADCRST2
TE21
TE22
CONVLED1
TE23
TE24
SLED_amb
TE25
TE26
ADCRST3
TE27
TE28
CONVLED_amb
TE29
TE30
PDNCYCLE
TE31
TE32
Figure 32. Timing Diagram
22
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8.3.6.3 Receiver Timing
The timing engine can be programmed to set the different phases of the receiver. The relative timings of the LED
phase, sampling phase, ADC reset phase, and ADC conversion phases are shown in Figure 33 and Table 7.
t1
LED2
t2
SLED2
ADCRST0
CONVLED2
t3
t4
t5
Figure 33. Receiver Timing Guidelines
Table 7. Receiver Timing Details
MIN
MAX
UNIT
µs
t1
t2
t3
t4
t5
Start of LED to start of sampling
Max [25, (0.2 × LED pulse duration)]
End of LED to start of ADC reset phase
Duration of ADC reset phase
2
Counts(1)
Counts
Count
µs
6
End of ADC reset phase to start of ADC conversion phase
Duration of ADC conversion phase(2)
2
2
(NUMAV + 2) × 200 × tADC + 15(3)
(1) Refers to one clock period of CLK_TE.
(2) See Figure 36 for notations of the clocking domain.
(3) tADC = 1 / fADC
.
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The fourth ADCRST signal (ADCRST3) in a period also defines the start of the ADC_RDY pulse. The rising edge
of the ADC_RDY signal can be used as an interrupt by the MCU to readout the registers corresponding to the
preceding four conversions in that period. If any of the four conversion phases are not needed, then their
duration can be set to 0. However, the corresponding ADCRSTx pulse must still be defined. All four ADCRSTx
pulses must be defined in order to generate the ADC_RDY pulse. A scheme of the ADC_RDY pulse generation
is shown in Figure 34. The ADC_RDY pulse timing is shown in Table 8.
Pulse Repetition Period
CONV1
CONV1'
ADCRST0
ADCRST1
CONV2
CONV2'
CONV3
CONV3'
ADCRST2
ADCRST3
CONV4
CONV4'
t7
ADC_RDY
(Generated by Device)
t6
Data in ADC Registers
ADC registers hold contents of CONV1, CONV2, CONV3, and CONV4.
… CONV1', CONV2', CONV3', CONV4'
Figure 34. ADC_RDY Generation Scheme
Table 8. ADC_RDY Timing Details
TYP
MAX
(NUMAV + 2) × 200 × tADC + 15
UNIT
µs
End of fourth ADC reset phase to start of
ADC_RDY pulse
t6
t7
(NUMAV + 1) × 200 × tADC
(1)
ADC_RDY pulse duration
tADC
µs
(1) If a larger pulse duration is needed for the ADC_RDY interrupt, use PROG_TG_EN to enable a programmable timing signal to come out
of the ADC_RDY pin. The location of the signal can be set using the PROG_TG_STC and PROG_TG_ENDC counts.
24
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8.3.6.4 Dynamic Power-Down Timing
The dynamic power-down feature can be used to shut down the receiver inside every cycle to save power, as
shown in Figure 35 and Table 9.
Count =
PRPCT
Count = 0
CONVLED2
CONVLED3
CONVLED1
CONVLED_amb
PDNCYCLE
t8
t9
Figure 35. Dynamic Power-Down Timing Diagram
Table 9. Dynamic Power-Down Timing Details
MIN
200
200
UNIT
µs
t8
t9
End of 4th conversion phase to the start of PDNCYCLE
End of PDNCYCLE to start of next period
µs
The timing controls for the PDNCYCLE pulse are shown in Table 10.
Table 10. Timing Controls for Dynamic Power-Down
TIMING SIGNAL
PDNCYCLESTC
PDNCYCLEENDC
DESCRIPTION
REGISTER ADDRESS (Hex)
TIMING EDGE(1)
TE31
Dynamic power-down start
Dynamic power-down end
32h
33h
TE32
(1) See Figure 32.
8.3.6.5 Sample Register Values
Table 11 lists a sample of the register settings for generating the different timing signals. These sample settings
correspond to CLK_INT = 4 MHz and a PRF of 100 Hz. Three LEDs are used in a cycle, each with a duty cycle
of 1%, corresponding to a pulse duration of 100 µs. The conversion durations are set in order to accommodate
four averages (NUMAV = 3). Two cases are described in Table 11: one for CLKDIV_PRF = 1 (CLK_TE = 4 MHz)
and the other for CLKDIV_PRF = 16 (CLK_TE = 250 kHz).
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Table 11. Sample Register Settings
NO DIVISION OF CLOCK TO TIMING
ENGINE CLOCK
ADC CLOCK TO TIMING ENGINE
CLOCK DIVIDED BY 16
(CLKDIV_PRF = 16)
SIGNAL(1)
REGISTER FIELD
(CLKDIV_PRF = 1)
TIME DURATION
(µs)
REGISTER
SETTING(2)
TIME DURATION
REGISTER
(µs)
SETTING(2)
PRF COUNTER
LED2
PRPCT
10000
39999(3)
10000
2499(3)
LED2LEDSTC
LED2LEDENDC
LED2STC
0
0
100
100
72
399
100
399
401
407
409
1468
401
800
24
7
SLED2
ADCRST0
CONVLED2
LED3
75
LED2ENDC
24
26
26
28
94
26
50
ADCRSTSTCT0
ADCRSTENDCT0
LED2CONVST
LED2CONVEND
LED3LEDSTC
LED3LEDENDC
1.75
265
100
4
268
100
ALED2STC\
LED3STC
501
800
33
50
SLED3
75
72
4
ALED2ENDC\
LED3ENDC
ADCRSTSTCT1
1470
1476
96
96
ADCRST1
CONVLED3
1.75
265
ADCRSTENDCT1
ALED2CONVST\
LED3CONVST
1478
2537
98
268
ALED2CONVEND\
LED3CONVEND
164
LED1LEDSTC
LED1LEDENDC
LED1STC
802
1201
902
52
76
LED1
SLED1
100
75
100
72
59
LED1ENDC
1201
2539
2545
2547
3606
1303
1602
3608
3614
3616
4675
5475
39199
76
ADCRSTSTCT2
ADCRSTENDCT2
LED1CONVST
LED1CONVEND
ALED1STC
166
166
168
234
85
ADCRST2
CONVLED1
SLED_AMB
1.75
265
4
268
72
75
ALED1ENDC
102
236
236
238
304
354
2449
ADCRSTSTCT3
ADCRSTENDCT3
ALED1CONVST
ALED1CONVEND
PDNCYCLESTC
PDNCYCLEENDC
ADCRST3
CONVLED_AMB
PDNCYCLE
1.75
265
4
268
8384
8431.25
(1) For signal names, see Figure 23.
(2) Time duration = (end count – start count + 1) / fTE
.
(3) For PRPCT, start count = 0.
26
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The timing described in Table 11 minimizes the active time, thereby enabling the signal chain to be in the
dynamic power-down state for the maximum fraction of time. In this timing, the LED active phase overlaps with
the conversion phase corresponding to a previous LED. The ground bounce from the LED switching can couple
into the receiver and cause a small interference between one phase and the next. In most intended applications,
this bounce is not expected to cause any problems. However, if the lowest level of interference across phases
must be attained, the timing registers can be programmed as shown in Table 12.
Table 12. Sample Register Settings for Low Interference Across Phases
NO DIVISION OF CLOCK TO TIMING ENGINE CLOCK
(CLKDIV_PRF = 1)
SIGNAL(1)
REGISTER FIELD
TIME DURATION (µs)
REGISTER SETTING
PRF COUNTER
LED2
PRPCT
10000
39999
0
LED2LEDSTC
LED2LEDENDC
LED2STC
99.75
74.75
1.75
398
100
SLED2
ADCRST0
CONVLED2
LED3
LED2ENDC
398
ADCRSTSTCT0
ADCRSTENDCT0
LED2CONVST
LED2CONVEND
LED3LEDSTC
LED3LEDENDC
5600
5606
5608
6067
400
115
99.75
798
ALED2STC\
LED3STC
500
798
SLED3
74.75
1.75
115
ALED2ENDC\
LED3ENDC
ADCRSTSTCT1
6069
6075
ADCRST1
CONVLED3
ADCRSTENDCT1
ALED2CONVST\
LED3CONVST
6077
6536
ALED2CONVEND\
LED3CONVEND
LED1LEDSTC
LED1LEDENDC
LED1STC
800
1198
900
LED1
SLED1
99.75
74.75
1.75
LED1ENDC
1198
6538
6544
6546
7006
1300
1598
7008
7014
7016
7475
7675
39199
ADCRSTSTCT2
ADCRSTENDCT2
LED1CONVST
LED1CONVEND
ALED1STC
ADCRST2
CONVLED1
SLED_AMB
ADCRST3
CONVLED_AMB
115.25
74.75
1.75
ALED1ENDC
ADCRSTSTCT3
ADCRSTENDCT3
ALED1CONVST
ALED1CONVEND
PDNCYCLESTC
PDNCYCLEENDC
115
PDNCYCLE
7881.25
(1) For signal names, see Figure 23.
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8.4 Device Functional Modes
8.4.1 Power Modes
The AFE has the following power modes:
1. Normal mode.
2. Hardware power-down mode (PWDN): this mode is set using the RESETZ pin. When the RESETZ pin is
pulled low for more than 200 µs, the device enters hardware power-down mode where the power
consumption is very low (of a few µA).
3. Software power-down mode (PDNAFE) using a register bit.
4. Dynamic power-down mode: this mode is enabled by setting the start and end points of the PDN_CYCLE
signal that is controlled using the timing engine. During the PDN_CYCLE high phase, the functional blocks
(as selected by the DYNAMICx bits) are powered down. When powering down the TIA in dynamic power-
down mode, consideration must be given to the dynamics of the photodiode. When the TIA is powered down,
the feedback mechanism is no longer available to maintain zero bias across the photodiode, resulting in a
voltage drift across the photodiode. When the AFE comes out of dynamic power-down into active mode, a
transient recovery time for the photodiode results. Additionally, the INP, INM pins can be shorted through a
switch to an internal reference voltage (VCM) to keep the photodiode in zero bias whenever the TIA is in
power-down mode. Maintaining zero bias across the photodiode is accomplished by setting the
ENABLE_INPUT_SHORT bit to 1. By setting this bit in conjunction with the DYNAMIC3 bit, the dynamics of
the photodiode can be better controlled during the dynamic power-down mode.
8.4.2 RESET Modes
The AFE has internal registers that must be reset before valid operation. There are two ways to reset the device:
1. Either through the RESETZ pin (a reset signal can be issued by pulsing the RESETZ pin low for a duration of
time between 25 to 50 µs) or
2. A software reset via the SW_RESET register bit.
8.4.3 Clocking Modes
The AFE has an internal oscillator that can generate a 4-MHz clock. This clock can be made to come out of the
CLK pin for use by the rest of the system. The default mode is to use an external clock. The frequency range of
this external clock is between 4 MHz to 60 MHz. A programmable internal division ratio between 1 to 12 must be
set so that the divided clock is between 4 MHz to 6 MHz. For high-accuracy measurements, operating the AFE
using an input (external) clock with high accuracy is preferable. If a high-accuracy measurement is required when
using the internal oscillator, a correction scheme can be used in the MCU to digitally compensate for the
inaccuracy in the oscillator. One method of this approach is to accurately estimate the PRF by measuring the
ADC_RDY periodicity in terms of a high-accuracy MCU clock (for example, a 32-kHz clock) to establish the
accurate PRF. This information can then be used to digitally correct the heart rate computation.
8.4.4 PRF Programmability
By default, the internal clock is 4 MHz. This clock also goes to the timing engine that has a 16-bit counter. The
maximum setting of this counter (all 16 bits set to 1) determines the lowest value of PRF, resulting in a minimum
PRF of 61 Hz. To extend the lower range of PRF, an independent programmable divider is introduced in the
clock going to the timing engine. By programming this divider between 1 to 16 with the CLKDIV_PRF register
control, the lower range of PRF can be extended from 61 Hz to approximately 4 Hz (limit the minimum PRF to
10 Hz). The various clocking domains and controls are described in Figure 36 and Table 13.
28
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Device Functional Modes (continued)
To ADC
CLKDIV_CLKOUT
ENABLE_CLKOUT
OSC_ENABLE
/
CLK_INT
4-MHz
Oscillator
1
0
fINT
CLK_ADC
CLK_TE
ADC_RDY
fPRF
CLK
/
Timing Engine
(TE)
/
CLK_EXT
fEXT
fTE
fADC
CLKDIV_PRF
OSC_ENABLE
CLKDIV_EXTMODE
Figure 36. Clocking Domains Diagram
Table 13. Clock Domains and Operating Ranges
CLOCK
CLK_INT
DESCRIPTION
FREQUENCY
FREQUENCY RANGE
COMMENTS
Clock generated by the internal
oscillator
Internal clock when the oscillator is
enabled
(1)
fINT
4 MHz
Set the division ratio with
CLKDIV_EXTMODE so that CLK_ADC is
4 MHz to 6 MHz
CLK_EXT
External clock
fEXT
4 MHz to 60 MHz
Clock used by the ADC for
conversion
Selected as either an internal clock or a
divided version of the external clock
CLK_ADC
CLK_TE
fADC
fTE
4 MHz to 6 MHz
Clock used by the timing engine
fADC divided by 1 to 16
Division ratio is set by CLKDIV_PRF
Set by PRPCT and fTE
Interrupt to MCU at the same
rate as the PRF
Limit to 10 Hz-1000 Hz, limited to 1000 /
(division ratio as set by CLKDIV_PRF)
ADC_RDY
fPRF
(1) See the Electrical Characteristics table for the accuracy of the internal oscillator.
8.4.5 Averaging Modes
To reduce the noise, the input to the ADC (sampled on the CSAMPx capacitors) can be converted by the ADC
multiple times and averaged. The number of averages is set using the NUMAV register control based on
Equation 1:
Number of Averages = (NUMAV + 1)
(1)
By default, NUMAV = 0. Therefore, the default mode corresponds to when the ADC converts its input one time in
each of the four phases and stores the content in the register corresponding to that phase.
When NUMAV is programmed (for example if NUMAV = 3), the ADC converts its input four times in each phase,
averages the four conversions, and stores the averaged value in the register corresponding to that phase.
Averaging only helps in reducing ADC noise and not the front end noise because the input to the ADC is the
same sampled voltage across all the ADC conversions used to generate the average (this voltage corresponds
to the voltage sampled on the four CSAMPx capacitors in Figure 23). The number of samples that can be
averaged ranges from 1 to 16 (when NUMAV is programmed from 0 to 15). A higher number of averages results
in larger conversion times; see Table 7.
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Averaging is implemented in the following manner:
The number of ADC samples corresponding to the number of averages (NUMAV + 1) are accumulated, as
shown in Equation 2.
where
•
ADCi = the ith sample converted by the ADC.
(2)
The accumulator output (SUMADC) is then divided by a factor D that is obtained by D = 128 ÷ X , with X being
an integer.
The averaged output is shown in Equation 3:
ADCOUT = SUMADC ÷ D
where
•
D = 128 ÷ X, with X being an integer.
(3)
This implementation gives an averaging function that is exact when the number of averages is a power of 2 but
deviates from ideal values for other settings, as shown in Table 14.
Table 14. Averaging Mode Settings
NUMAV
NUMBER OF AVERAGES
INTEGER (X)
DIVISION FACTOR (D)
0
1
1
2
128
64
43
32
26
21
18
16
14
13
12
11
10
9
1.0
2.0
2
3
2.97
4.0
3
4
4
5
4.92
6.10
7.11
8.0
5
6
6
7
7
8
8
9
9.14
9.85
10.67
11.64
12.8
14.22
14.22
16.0
9
10
11
12
13
14
15
16
10
11
12
13
14
15
9
8
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8.4.6 Decimation Mode
The AFE4404 has a decimation mode that can be used to improve the performance at low pulse repetition
frequencies (PRFs). In this mode, up to N (N = 2, 4, 8, or 16) consecutive data samples can be averaged. The
averaged output comes out one time every N clock cycles. The ADC_RDY frequency also reduces to PRF / N.
A timing diagram is shown in Figure 37 for where the decimation factor = 4 and PRF = 100 Hz. Figure 37 is only
intended to illustrate the change in periodicity of ADC_RDY and the update rate of the registers relative to the
pulse repetition period. However, the timing of all other signals continues to be as per the descriptions mentioned
in the Timing Engine section.
LED On
PRF Setting,
100 Hz
ADC Conversion of
(LED2-Ambient2)
Data 5
Data 5
Data 6
Data 6
Data 7
Data 7
Data 8
Data 8
Data 9
Data 9
Data 10
Data 10
Data 11
Data 11
Data 12
Data 12
Data 4
Data 4
Register 2Eh
Average of Data 1, 2, 3, 4
Average of Data 5, 6, 7, 8
Register 3Fh
ADC_RDY
25-Hz Frequency
Figure 37. Decimation Mode Enabled Timing Diagram
(Decimation Factor = 4, PRF = 100 Hz)
8.4.6.1 Decimation Mode Power and Performance
The main advantage of the decimation mode is that this mode can be used to reduce the readout rate of the
MCU because the data rate reduces by the decimation factor. Normally, reducing the data rate leads to SNR
loss. However, with decimation mode, there is no SNR loss regardless of the lower data rate because of the
averaging of consecutive samples. Table 15 compares different modes of operation.
Table 15. Different Modes of Operation
RATE OF DEVICE SAMPLES
MODE
RATE OF MCU DATA READS
RELATIVE PERFORMANCE
AND CONVERSIONS
No decimation, 100-Hz PRF
No decimation, 25-Hz PRF
100 Hz
100 Hz
25 Hz
Reference
SNR is approximately 6 dB lower
than reference
25 Hz
4X decimation mode, 100-Hz
PRF
100 Hz
25 Hz
SNR is comparable to reference
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8.5 Register Map
Table 16. Register Map(1)
ADDRESS
(Hex)
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
00h
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LED2STC
LED2ENDC
LED1LEDSTC
LED1LEDENDC
ALED2STC\LED3STC
ALED2ENDC\LED3ENDC
LED1STC
LED1ENDC
LED2LEDSTC
LED2LEDENDC
ALED1STC
ALED1ENDC
LED2CONVST
LED2CONVEND
ALED2CONVST\LED3CONVST
ALED2CONVEND\LED3CONVEND
LED1CONVST
LED1CONVEND
ALED1CONVST
ALED1CONVEND
ADCRSTSTCT0
ADCRSTENDCT0
ADCRSTSTCT1
ADCRSTENDCT1
ADCRSTSTCT2
ADCRSTENDCT2
ADCRSTSTCT3
ADCRSTENDCT3
PRPCT
(1) After reset, all register bits are reset to 0.
32
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Register Map (continued)
Table 16. Register Map(1) (continued)
ADDRESS
(Hex)
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
1Eh
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
NUMAV
20h
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TIA_CF_SEP
TIA_CF
TIA_GAIN_SEP
TIA_GAIN
21h
22h
23h
28h
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ILED3
ILED2
ILED1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
29h
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CLKDIV_CLKOUT
2Ah
2Bh
2Ch
2Dh
2Eh
2Fh
LED2VAL
ALED2VAL\LED3VAL
LED1VAL
ALED1VAL
LED2-ALED2VAL(2)
LED1-ALED1VAL
31h
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CLKDIV_EXTMODE
32h
PDNCYCLESTC
(2) Ignore the contents of this register when LED3 is used.
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Register Map (continued)
Table 16. Register Map(1) (continued)
ADDRESS
(Hex)
33h
34h
35h
36h
37h
39h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
PDNCYCLEENDC
PROG_TG_STC
PROG_TG_ENDC
LED3LEDSTC
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LED3LEDENDC
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CLKDIV_PRF
I_OFFDAC_AMB2\
I_OFFDAC_LED3
3Ah
0
0
0
0
I_OFFDAC_LED2
I_OFFDAC_AMB1
I_OFFDAC_LED1
DEC_E
N
3Dh
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DEC_FACTOR
0
3Fh
40h
AVG_LED2-ALED2VAL
AVG_LED1-ALED1VAL
34
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8.5.1 Register 0h (address = 0h) [reset = 0h]
Figure 38. Register 0h
23
0
22
0
21
0
20
0
19
0
18
0
17
16
0
W-0h
9
0
W-0h
8
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
0
0
0
0
0
0
0
0
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
2
W-0h
1
W-0h
0
TM_COUNT_
RST
0
0
0
0
SW_RESET
W-0h
0
REG_READ
W-0h
W-0h
W-0h
W-0h
W-0h
W-0h
W-0h
LEGEND: W = Write only; -n = value after reset
Table 17. Register 0h Field Descriptions
Bit
23-4
3
Field
Type
W
Reset
0h
Description
0
Must write 0.
SW_RESET
W
0h
Self-clearing reset bit.
For a software reset, write 1.
2
1
0
0
W
W
W
0h
0h
0h
Must write 0.
TM_COUNT_RST
REG_READ
Used to suspend the count and keep the counter in a reset state.
Register readout enable for write registers
(not needed for ADC output registers).
0 = Register write mode
1 = Enables the readout of write registers
8.5.2 Register 1h (address = 1h) [reset = 0h]
Figure 39. Register 1h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED2STC
R/W-0h
7
6
5
4
3
2
1
0
LED2STC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 18. Register 1h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED2STC
R/W
0h
Sample LED2 start
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8.5.3 Register 2h (address = 2h) [reset = 0h]
Figure 40. Register 2h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED2ENDC
R/W-0h
7
6
5
4
3
2
1
0
LED2ENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 19. Register 2h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED2ENDC
R/W
0h
Sample LED2 end
8.5.4 Register 3h (address = 3h) [reset = 0h]
Figure 41. Register 3h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED1LEDSTC
R/W-0h
7
6
5
4
3
2
1
0
LED1LEDSTC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 20. Register 3h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
Must write 0.
LED1 start
23-16
15-0
0
LED1LEDSTC
R/W
0h
36
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8.5.5 Register 4h (address = 4h) [reset = 0h]
Figure 42. Register 4h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED1LEDENDC
R/W-0h
7
6
5
4
3
2
1
0
LED1LEDENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 21. Register 4h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
Must write 0.
LED1 end
23-16
15-0
0
LED1LEDENDC
R/W
0h
8.5.6 Register 5h (address = 5h) [reset = 0h]
Figure 43. Register 5h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED2STC\LED3STC
R/W-0h
7
6
5
4
3
2
1
0
ALED2STC\LED3STC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 22. Register 5h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ALED2STC\LED3STC
R/W
0h
Sample ambient 2 (or sample LED3) start
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8.5.7 Register 6h (address = 6h) [reset = 0h]
Figure 44. Register 6h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED2ENDC\LED3ENDC
R/W-0h
7
6
5
4
3
2
1
0
ALED2ENDC\LED3ENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 23. Register 6h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ALED2ENDC\LED3ENDC
R/W
0h
Sample ambient 2 (or sample LED3) end
8.5.8 Register 7h (address = 7h) [reset = 0h]
Figure 45. Register 7h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED1STC
R/W-0h
7
6
5
4
3
2
1
0
LED1STC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 24. Register 7h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED1STC
R/W
0h
Sample LED1 start
38
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8.5.9 Register 8h (address = 8h) [reset = 0h]
Figure 46. Register 8h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED1ENDC
R/W-0h
7
6
5
4
3
2
1
0
LED1ENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 25. Register 8h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED1ENDC
R/W
0h
Sample LED1 end
8.5.10 Register 9h (address = 9h) [reset = 0h]
Figure 47. Register 9h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED2LEDSTC
R/W-0h
7
6
5
4
3
2
1
0
LED2LEDSTC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 26. Register 9h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
Must write 0.
LED2 start
23-16
15-0
0
LED2LEDSTC
R/W
0h
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8.5.11 Register Ah (address = Ah) [reset = 0h]
Figure 48. Register Ah
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED2LEDENDC
R/W-0h
7
6
5
4
3
2
1
0
LED2LEDENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 27. Register Ah Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
Must write 0.
LED2 end
23-16
15-0
0
LED2LEDENDC
R/W
0h
8.5.12 Register Bh (address = Bh) [reset = 0h]
Figure 49. Register Bh
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED1STC
R/W-0h
7
6
5
4
3
2
1
0
ALED1STC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 28. Register Bh Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ALED1STC
R/W
0h
Sample ambient 1 start
40
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8.5.13 Register Ch (address = Ch) [reset = 0h]
Figure 50. Register Ch
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED1ENDC
R/W-0h
7
6
5
4
3
2
1
0
ALED1ENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 29. Register Ch Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ALED1ENDC
R/W
0h
Sample ambient 1 end
8.5.14 Register Dh (address = Dh) [reset = 0h]
Figure 51. Register Dh
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED2CONVST
R/W-0h
7
6
5
4
3
2
1
0
LED2CONVST
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 30. Register Dh Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED2CONVST
R/W
0h
LED2 convert phase start
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8.5.15 Register Eh (address = Eh) [reset = 0h]
Figure 52. Register Eh
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED2CONVEND
R/W-0h
7
6
5
4
3
2
1
0
LED2CONVEND
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 31. Register Eh Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED2CONVEND
R/W
0h
LED2 convert phase end
8.5.16 Register Fh (address = Fh) [reset = 0h]
Figure 53. Register Fh
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED2CONVST\LED3CONVST
R/W-0h
7
6
5
4
3
2
1
0
ALED2CONVST\LED3CONVST
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 32. Register Fh Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ALED2CONVST\LED3CONVST
R/W
0h
Ambient 2 (or LED3) convert phase start
42
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8.5.17 Register 10h (address = 10h) [reset = 0h]
Figure 54. Register 10h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED2CONVEND\LED3CONVEND
R/W-0h
7
6
5
4
3
2
1
0
ALED2CONVEND\LED3CONVEND
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 33. Register 10h Field Descriptions
Bit
Field
Type
Reset
0h
Description
23-16
15-0
0
W
Must write 0.
ALED2CONVEND\LED3CONVEND R/W
0h
Ambient 2 (or LED3) convert phase end
8.5.18 Register 11h (address = 11h) [reset = 0h]
Figure 55. Register 11h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED1CONVST
R/W-0h
7
6
5
4
3
2
1
0
LED1CONVST
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 34. Register 11h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED1CONVST
R/W
0h
LED1 convert phase start
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8.5.19 Register 12h (address = 12h) [reset = 0h]
Figure 56. Register 12h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED1CONVEND
R/W-0h
7
6
5
4
3
2
1
0
LED1CONVEND
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 35. Register 12h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED1CONVEND
R/W
0h
LED1 convert phase end
8.5.20 Register 13h (address = 13h) [reset = 0h]
Figure 57. Register 13h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED1CONVST
R/W-0h
7
6
5
4
3
2
1
0
ALED1CONVST
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 36. Register 13h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0
ALED1CONVST
R/W
0h
Ambient 1 convert phase start
44
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8.5.21 Register 14h (address = 14h) [reset = 0h]
Figure 58. Register 14h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ALED1CONVEND
R/W-0h
7
6
5
4
3
2
1
0
ALED1CONVEND
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 37. Register 14h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ALED1CONVEND
R/W
0h
Ambient 1 convert phase end
8.5.22 Register 15h (address = 15h) [reset = 0h]
Figure 59. Register 15h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTSTCT0
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTSTCT0
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 38. Register 15h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTSTCT0
R/W
0h
ADC reset phase 0 start
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8.5.23 Register 16h (address = 16h) [reset = 0h]
Figure 60. Register 16h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTENDCT0
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTENDCT0
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 39. Register 16h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTENDCT0
R/W
0h
ADC reset phase 0 end
8.5.24 Register 17h (address = 17h) [reset = 0h]
Figure 61. Register 17h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTSTCT1
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTSTCT1
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 40. Register 17h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTSTCT1
R/W
0h
ADC reset phase 1 start
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8.5.25 Register 18h (address = 18h) [reset = 0h]
Figure 62. Register 18h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTENDCT1
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTENDCT1
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 41. Register 18h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTENDCT1
R/W
0h
ADC reset phase 1 end
8.5.26 Register 19h (address = 19h) [reset = 0h]
Figure 63. Register 19h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTSTCT2
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTSTCT2
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 42. Register 19h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTSTCT2
R/W
0h
ADC reset phase 2 start
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8.5.27 Register 1Ah (address = 1Ah) [reset = 0h]
Figure 64. Register 1Ah
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTENDCT2
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTENDCT2
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 43. Register 1Ah Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTENDCT2
R/W
0h
ADC reset phase 2 end
8.5.28 Register 1Bh (address = 1Bh) [reset = 0h]
Figure 65. Register 1Bh
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTSTCT3
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTSTCT3
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 44. Register 1Bh Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTSTCT3
R/W
0h
ADC reset phase 3 start
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8.5.29 Register 1Ch (address = 1Ch) [reset = 0h]
Figure 66. Register 1Ch
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ADCRSTENDCT3
R/W-0h
7
6
5
4
3
2
1
0
ADCRSTENDCT3
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 45. Register 1Ch Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
ADCRSTENDCT3
R/W
0h
ADC reset phase 3 end
8.5.30 Register 1Dh (address = 1Dh) [reset = 0h]
Figure 67. Register 1Dh
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
PRPCT
R/W-0h
7
6
5
4
3
2
1
0
PRPCT
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 46. Register 1Dh Field Descriptions
Bit
Field
0
Type
W
Reset
0h
Description
23-16
15-0
Must write 0.
PRPCT
R/W
0h
These bits are the count value for the counter that sets the PRF.
The counter automatically counts until PRPCT and then returns back to
0 to start the next count.
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8.5.31 Register 1Eh (address = 1Eh) [reset = 0h]
Figure 68. Register 1Eh
23
0
22
0
21
0
20
0
19
0
18
0
17
16
0
W-0h
9
0
W-0h
8
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
0
0
0
0
0
0
0
TIMEREN
R/W-0h
0
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
2
W-0h
1
0
0
0
0
NUMAV
R/W-0h
W-0h
W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 47. Register 1Eh Field Descriptions
Bit
23-9
8
Field
Type
W
Reset
0h
Description
0
Must write 0.
TIMEREN
R/W
0h
0 = Timer module disabled
1 = Enables timer module. This bit enables the timing engine that can
be programmed to generate all clock phases for the synchronized
transmit drive, receive sampling, and data conversion.
7-4
3-0
0
W
0h
0h
Must write 0.
NUMAV
R/W
These bits determine the number of ADC averages. By programming a
higher ADC conversion time, the ADC can be set to do multiple
conversions and average these multiple conversions to achieve lower
noise. This programmability is set with the NUMAV bit control. The
number of samples that are averaged is represented by the decimal
equivalent of NUMAV + 1. For example, NUMAV = 0 represents no
averaging, NUMAV = 2 represents averaging of three samples, and
NUMAV = 15 represents averaging of 16 samples.
8.5.32 Register 20h (address = 20h) [reset = 0h]
Figure 69. Register 20h
23
22
0
21
0
20
19
18
0
17
16
0
0
0
0
0
W-0h
8
W-0h
W-0h
14
W-0h
13
W-0h
W-0h
11
W-0h
10
W-0h
15
12
9
ENSEPGAIN
0
0
0
W-0h
0
0
0
W-0h
0
R/W-0h
W-0h
6
W-0h
5
W-0h
3
W-0h
2
W-0h
0
7
0
4
1
0
TIA_CF_SEP
R/W-0h
TIA_GAIN_SEP
R/W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 48. Register 20h Field Descriptions
Bit
23-16
15
Field
Type
W
Reset
0h
Description
0
Must write 0.
ENSEPGAIN
R/W
0h
0 = Single TIA gain for all phases
1 = Enables two separate sets of TIA gains
14-6
5-3
0
W
0h
0h
0h
Must write 0.
TIA_CF_SEP
TIA_GAIN_SEP
R/W
R/W
When ENSEPGAIN = 1, TIA_CF_SEP is the control for the Cf2 setting.
2-0
When ENSEPGAIN = 1, TIA_GAIN_SEP is the control for the Rf2
setting.
50
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8.5.33 Register 21h (address = 21h) [reset = 0h]
Figure 70. Register 21h
23
0
22
0
21
0
20
0
19
0
18
0
17
16
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
W-0h
9
0
8
0
0
0
0
0
0
PROG_TG_EN
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
2
W-0h
1
W-0h
0
0
0
TIA_CF
R/W-0h
TIA_GAIN
R/W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 49. Register 21h Field Descriptions
Bit
23-9
8
Field
Type
W
Reset
0h
Description
0
Must write 0.
PROG_TG_EN
W
0h
This bit replaces the ADC_RDY output with a fully-
programmable signal from the timing engine. The start and end
points of this signal are set using the PROG_TG_STC and
PROG_TG_ENDC controls.
7-6
5-3
0
W
0h
0h
Must write 0.
TIA_CF
R/W
When ENSEPGAIN = 0, these bits control the Cf setting (both
Cf1 and Cf2); see Table 51 for details.
When ENSEPGAIN = 1, these bits control the Cf1 setting.
2-0
TIA_GAIN
R/W
0h
When ENSEPGAIN = 0, these bits control the Rf setting (both
Rf1 and Rf2); see Table 50 for details.
When ENSEPGAIN = 1, these bits control the Rf1 setting.
Table 50. TIA_GAIN Register Settings
TIA_GAIN, TIA_GAIN_SEP REGISTER VALUE
Rf
0
1
2
3
4
5
6
7
500 kΩ
250 kΩ
100 kΩ
50 kΩ
25 kΩ
10 kΩ
1 MΩ
2 MΩ
Table 51. TIA_CF Register Settings
TIA_CF, TIA_CF_SEP REGISTER VALUE
Cf
0
1
2
3
4
5
6
7
5 pF
2.5 pF
10 pF
7.5 pF
20 pF
17.5 pF
25 pF
22.5 pF
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8.5.34 Register 22h (address = 22h) [reset = 0h]
Figure 71. Register 22h
23
0
22
0
21
0
20
0
19
0
18
0
17
9
16
ILED3
R/W-0h
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
8
0
ILED3
ILED2
R/W-0h
R/W-0h
7
6
5
4
3
2
1
ILED2
ILED1
R/W-0h
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 52. Register 22h Field Descriptions
Bit
23-18
17-12
11-6
5-0
Field
0
Type
W
Reset
0h
Description
Must write 0.
ILED3
ILED2
ILED1
R/W
R/W
R/W
0h
LED3 current control
LED2 current control
0h
0h
LED1 current control. Increments of the LED1 current setting are
listed in Table 53.
Table 53. ILED1 Register Settings
ILED1, ILED2, ILED3 REGISTER VALUES
LED CURRENT SETTING (mA)
0
1
0
0.8
1.6
2.4
…
2
3
…
63
50
52
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8.5.35 Register 23h (address = 23h) [reset = 0h]
Figure 72. Register 23h
23
0
22
21
0
20
DYNAMIC1
R/W-0h
12
19
18
0
17
ILED_2X
R/W-0h
9
16
0
W-0h
14
0
W-0h
11
0
W-0h
8
W-0h
15
W-0h
13
W-0h
10
0
DYNAMIC2
R/W-0h
6
0
0
0
0
OSC_ENABLE
R/W-0h
1
0
W-0h
7
W-0h
5
W-0h
W-0h
3
W-0h
2
W-0h
0
4
0
0
0
DYNAMIC3
R/W-0h
DYNAMIC4
R/W-0h
0
PDNRX
R/W-0h
PDNAFE
R/W-0h
W-0h
W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 54. Register 23h Field Descriptions
Bit
23-21
20
Field
Type
W
Reset
0h
Description
0
Must write 0.
DYNAMIC1
R/W
0h
0 = Transmitter is not powered down
1 = Transmitter is powered down in dynamic power-down mode
19-18
17
0
W
0h
0h
Must write 0.
ILED_2X
R/W
0 = LED current range is 0 mA to 50 mA
1 = LED current range is 0 mA to 100 mA
16-15
14
0
W
0h
0h
Must write 0.
DYNAMIC2
R/W
0 = ADC is not powered down
1 = ADC is powered down in dynamic power-down mode
13-10
9
0
W
0h
0h
Must write 0.
OSC_ENABLE
R/W
0 = External clock mode (default). In this mode, the CLK pin
functions as an input pin where the external clock can be input.
1 = Enables oscillator mode. In this mode, the 4-MHz internal
oscillator is enabled.
8-5
4
0
W
0h
0h
Must write 0.
DYNAMIC3
R/W
0 = TIA is not powered down
1 = TIA is powered down in dynamic power-down mode
3
DYNAMIC4
R/W
0h
0 = Rest of ADC is not powered down
1 = Rest of ADC is powered down in dynamic power-down mode
2
1
0
W
0h
0h
Must write 0.
PDNRX
R/W
0 = Normal mode
1 = RX portion of the AFE is powered down
0
PDNAFE
R/W
0h
0 = Normal mode
1 = Entire AFE is powered down
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8.5.36 Register 29h (address = 29h) [reset = 0h]
Figure 73. Register 29h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
ENABLE_
CLKOUT
0
0
0
0
0
0
0
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
2
R/W-0h
1
W-0h
0
0
0
0
CLKDIV_CLKOUT
R/W-0h
0
W-0h
W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 55. Register 29h Field Descriptions
Bit
23-10
9
Field
Type
W
Reset
0h
Description
0
Must write 0.
ENABLE_CLKOUT
R/W
0h
In internal clock mode, the internally-generated clock can be
output on the CLK pin.
0 = Disables the clock output
1 = Enables CLKOUT generation and buffering on the CLK pin.
The frequency of the clock output on the CLK pin (in internal
clock mode) can be set using a programmable divider controlled
by the CLKDIV_CLKOUT register bit.
8-5
4-1
0
W
0h
0h
Must write 0.
CLKDIV_CLKOUT
R/W
Set the frequency of the clock output on the CLK pin (in the
internal clock mode), as shown in Table 56.
Table 56. CLKDIV_CLKOUT Register Settings
CLKDIV_CLKOUT REGISTER SETTINGS
DIVISION RATIO
FREQUENCY OF OUTPUT CLOCK IN MHz
0
1
4
2
1
2
2
4
1
3
8
0.5
4
5
16
32
0.25
0.125
0.0625
0.03125
Do not use
6
64
7
128
8..15
Do not use
54
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8.5.37 Register 2Ah (address = 2Ah) [reset = 0h]
Figure 74. Register 2Ah
23
15
7
22
14
6
21
13
5
20
12
4
19
11
3
18
10
2
17
9
16
8
LED2VAL
R-0h
LED2VAL
R-0h
1
0
LED2VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 57. Register 2Ah Field Descriptions
Bit
Field
Type
Reset
Description
23-0
LED2VAL
R
0h
These bits are the LED2 output code in 24-bit, twos complement
format.
8.5.38 Register 2Bh (address = 2Bh) [reset = 0h]
Figure 75. Register 2Bh
23
15
7
22
14
6
21
13
5
20
19
18
10
2
17
9
16
8
ALED2VAL\LED3VAL
R-0h
12
11
ALED2VAL\LED3VAL
R-0h
4
3
1
0
ALED2VAL\LED3VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 58. Register 2Bh Field Descriptions
Bit
Field
Type
Reset
Description
23-0
ALED2VAL\LED3VAL
R
0h
These bits are the ambient 2 or LED3 output code in 24-bit, twos
complement format.
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8.5.39 Register 2Ch (address = 2Ch) [reset = 0h]
Figure 76. Register 2Ch
23
15
7
22
14
6
21
13
5
20
12
4
19
11
3
18
10
2
17
9
16
8
LED1VAL
R-0h
LED1VAL
R-0h
1
0
LED1VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 59. Register 2Ch Field Descriptions
Bit
Field
Type
Reset
Description
23-0
LED1VAL
R
0h
These bits are the LED1 output code in 24-bit, twos complement
format.
8.5.40 Register 2Dh (address = 2Dh) [reset = 0h]
Figure 77. Register 2Dh
23
15
7
22
14
6
21
13
5
20
19
18
10
2
17
9
16
8
ALED1VAL
R-0h
12
4
11
3
ALED1VAL
R-0h
1
0
ALED1VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 60. Register 2Dh Field Descriptions
Bit
Field
Type
Reset
Description
23-0
ALED1VAL
R
0h
These bits are the ambient 1 output code in 24-bit, twos
complement format.
56
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8.5.41 Register 2Eh (address = 2Eh) [reset = 0h]
Figure 78. Register 2Eh
23
15
7
22
14
6
21
13
5
20
LED2-ALED2VAL
R-0h
19
18
10
2
17
9
16
8
12
11
LED2-ALED2VAL
R-0h
4
3
1
0
LED2-ALED2VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 61. Register 2Eh Field Descriptions
Bit
Field
Type
Reset
Description
23-0
LED2-ALED2VAL(1)
R
0h
These bits are the LED2-ambient2 output code in 24-bit, twos
complement format.
(1) Ignore the content of this register when LED3 is used.
8.5.42 Register 2Fh (address = 2Fh) [reset = 0h]
Figure 79. Register 2Fh
23
15
7
22
14
6
21
13
5
20
19
18
10
2
17
9
16
8
LED1-ALED1VAL
R-0h
12
11
LED1-ALED1VAL
R-0h
4
3
1
0
LED1-ALED1VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 62. Register 2Fh Field Descriptions
Bit
Field
Type
Reset
Description
23-0
LED1-ALED1VAL
R
0h
These bits are the LED1-ambient1 output code in 24-bit, twos
complement format.
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8.5.43 Register 31h (address = 31h) [reset = 0h]
Figure 80. Register 31h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
PD_
DISCONNECT
0
0
0
0
0
0
0
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
2
W-0h
1
W-0h
0
ENABLE_
INPUT_
SHORT
0
0
0
0
CLKDIV_EXTMODE
R/W-0h
W-0h
W-0h
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 63. Register 31h Field Descriptions
Bit
23-11
10
Field
Type
W
Reset
0h
Description
0
Must write 0.
PD_DISCONNECT
W
0h
This bit disconnects the PD signals (INP, INM) from the TIA
inputs. When enabled, the current input to the TIA is determined
completely by the offset cancellation DAC current (I_OFFDAC).
Note that in this mode, the AFE no longer sets the bias for the
PD.
9-6
5
0
W
0h
0h
Must write 0.
ENABLE_INPUT_SHORT
R/W
INP, INN are shorted to VCM whenever the TIA is in power-
down.
4-3
2-0
0
W
0h
0h
Must write 0.
CLKDIV_EXTMODE
R/W
These bits are used to set the division ratio to allow flexible
clocking in external clock mode. For details, see Table 64.
Table 64. CLKDIV_EXTMODE Register Settings
ALLOWED FREQUENCY RANGE OF
EXTERNAL CLOCK IN MHz
CLKDIV_EXTMODE REGISTER SETTINGS
DIVISION RATIO
0
1
2
3
4
5
6
7
2
8-12
32-48
8
Do not use
Do not use
48-60
12
4
16-24
1
6
4-6
24-36
Do not use
Do not use
58
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8.5.44 Register 32h (address = 32h) [reset = 0h]
Figure 81. Register 32h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
PDNCYCLESTC
R/W-0h
7
6
5
4
3
2
1
0
PDNCYCLESTC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 65. Register 32h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
PDNCYCLESTC
R/W
0h
PDN_CYCLE start
8.5.45 Register 33h (address = 33h) [reset = 0h]
Figure 82. Register 33h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
PDNCYCLEENDC
R/W-0h
7
6
5
4
3
2
1
0
PDNCYCLEENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 66. Register 33h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
PDNCYCLEENDC
R/W
0h
PDN_CYCLE end
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8.5.46 Register 34h (address = 34h) [reset = 0h]
Figure 83. Register 34h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
PROG_TG_STC
W-0h
7
6
5
4
3
2
1
0
PROG_TG_STC
W-0h
LEGEND: W = Write only; -n = value after reset
Table 67. Register 34h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
PROG_TG_STC
W
0h
These bits define the start time for the programmable timing
engine signal that can replace ADC_RDY.
8.5.47 Register 35h (address = 35h) [reset = 0h]
Figure 84. Register 35h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
PROG_TG_ENDC
W-0h
7
6
5
4
3
2
1
0
PROG_TG_ENDC
W-0h
LEGEND: W = Write only; -n = value after reset
Table 68. Register 35h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
PROG_TG_ENDC
W
0h
These bits define the end time for the programmable timing
engine signal that can replace ADC_RDY.
60
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8.5.48 Register 36h (address = 36h) [reset = 0h]
Figure 85. Register 36h
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED3LEDSTC
R/W-0h
7
6
5
4
3
2
1
0
LED3LEDSTC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 69. Register 36h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED3LEDSTC
R/W
0h
LED3 start. If LED3 is not used, set these register bits to '0'.
8.5.49 Register 37h (address = 37h) [reset = 0h]
Figure 86. Register 37h
23
0
22
0
21
0
20
19
18
0
17
0
16
0
0
0
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
W-0h
8
LED3LEDENDC
R/W-0h
7
6
5
4
3
2
1
0
LED3LEDENDC
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 70. Register 37h Field Descriptions
Bit
Field
Type
W
Reset
0h
Description
23-16
15-0
0
Must write 0.
LED3LEDENDC
R/W
0h
LED3 end. If LED3 is not used, set these register bits to '0'.
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8.5.50 Register 39h (address = 39h) [reset = 0h]
Figure 87. Register 39h
23
0
22
0
21
0
20
0
19
0
18
0
17
16
0
0
W-0h
8
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
W-0h
9
0
0
0
0
0
0
0
W-0h
0
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
2
W-0h
0
1
0
0
0
0
0
CLKDIV_PRF
R/W-0h
W-0h
W-0h
W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 71. Register 39h Field Descriptions
Bit
23-3
2-0
Field
Type
W
Reset
0h
Description
0
Must write 0.
CLKDIV_PRF
R/W
0h
Clock division ratio for the clock to the timing engine.
For details, see Table 72.
Table 72. CLKDIV_PRF Register Settings
CLKDIV_PRF
REGISTER SETTINGS
FREQUENCY OF THE TIMING CLOCK in
MHz (When the ADC Clock is 4 MHz)
LOWEST PRF SETTING
DIVISION RATIO
(In Hz(1)
)
0
1
2
3
4
5
6
7
1
4
61
Do not use
Do not use
Do not use
Do not use
Do not use
Do not use
Do not use
Do not use
Do not use
2
4
2
1
31
15
8
8
0.5
0.25
16
4
(1) Limit to 10 Hz.
62
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8.5.51 Register 3Ah (address = 3Ah) [reset = 0h]
Figure 88. Register 3Ah
23
0
22
0
21
0
20
0
19
18
10
2
17
16
8
POL_OFFDAC
_LED2
I_OFFDAC_LED2
W-0h
15
W-0h
14
W-0h
13
W-0h
12
R/W-0h
11
R/W-0h
9
I_OFFDAC_
LED2
POL_OFFDAC
_AMB1
POL_OFFDAC
_LED1
I_OFFDAC_
LED1
I_OFFDAC_AMB1
R/W-0h
R/W-0h
7
R/W-0h
6
R/W-0h
1
R/W-0h
0
5
4
3
POL_OFFDAC
_AMB2\
POL_OFFDAC
_LED3
I_OFFDAC_LED1
R/W-0h
I_OFFDAC_AMB2\I_OFFDAC_LED3
R/W-0h
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 73. Register 3Ah Field Descriptions
Bit
23-20
19
Field
Type
W
Reset
0h
Description
0
Must write 0.
POL_OFFDAC_LED2
I_OFFDAC_LED2
POL_OFFDAC_AMB1
I_OFFDAC_AMB1
POL_OFFDAC_LED1
I_OFFDAC_LED1
R/W
R/W
R/W
R/W
R/W
R/W
0h
Offset cancellation DAC polarity for LED2
Offset cancellation DAC setting forLED2
18-15
14
0h
0h
Offset cancellation DAC polarity for ambient 1
Offset cancellation DAC setting for ambient 1
Offset cancellation DAC polarity for LED1
13-10
9
0h
0h
8-5
0h
Offset cancellation DAC setting for LED1, as described in
Table 74.
4
POL_OFFDAC_AMB2\POL_OFFDAC_LED3
I_OFFDAC_AMB2\I_OFFDAC_LED3
R/W
R/W
0h
0h
Offset cancellation DAC polarity for ambient 2 (or LED3)
Offset cancellation DAC setting for ambient 2 (or LED3)
3-0
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Table 74. I_OFFDAC Register Settings(1)(2)
OFFSET CANCELLATION DAC CURRENT OFFSET CANCELLATION DAC CURRENT
I_OFFDAC REGISTER SETTINGS
(µA) WITH POL_OFFDAC = 0
(µA) WITH POL_OFFDAC = 1
0
1
0
0
0.47
0.93
1.4
–0.47
–0.93
–1.4
2
3
4
1.87
2.33
2.8
–1.87
–2.33
–2.8
5
6
7
3.27
3.73
4.2
–3.27
–3.73
–4.2
8
9
10
11
12
13
14
15
4.67
5.13
5.6
–4.67
–5.13
–5.6
6.07
6.53
7
–6.07
–6.53
–7
(1) I_OFFDAC can correspond to one of the four phases. POL_OFFDAC corresponds to the polarity control for the same phase.
(2) The offset cancellation DAC is not trimmed at production and, therefore, the value of the full-scale current can vary across units by
±20%.
64
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8.5.52 Register 3Dh (address = 3Dh) [reset = 0h]
Figure 89. Register 3Dh
23
0
22
0
21
0
20
0
19
0
18
17
16
0
0
W-0h
9
0
W-0h
8
W-0h
15
W-0h
14
W-0h
13
W-0h
12
W-0h
11
W-0h
10
0
0
0
0
0
0
W-0h
0
0
W-0h
7
W-0h
6
W-0h
5
W-0h
4
W-0h
3
W-0h
1
W-0h
0
2
0
0
DEC_EN
R/W-0h
0
DEC_FACTOR
R/W-0h
0
W-0h
W-0h
W-0h
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 75. Register 3Dh Field Descriptions
Bit
23-6
5
Field
0
Type
W
Reset
0h
Description
Must write 0.
DEC_EN
R/W
0h
0 = Decimation mode disabled
1 = Decimation mode enabled
4
0
W
0h
0h
Must write 0.
3-1
DEC_FACTOR
R/W
Decimation factor (how many samples are to be
averaged); see Table 76 for details.
0
0
W
0h
Must write 0.
Table 76. DEC_FACTOR Register Settings
DEC_FACTOR REGISTER SETTINGS
DECIMATION FACTOR
0
1
1
2
2
4
3
8
16
4
5-8
Do not use
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8.5.53 Register 3Fh (address = 3Fh) [reset = 0h]
Figure 90. Register 3Fh
23
15
7
22
14
6
21
13
5
20
19
18
10
2
17
9
16
8
AVG_LED2-ALED2VAL
R-0h
12
11
AVG_LED2-ALED2VAL
R-0h
4
3
1
0
AVG_LED2-ALED2VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 77. Register 3Fh Field Descriptions
Bit
Field
Type
Reset
Description
23-0
AVG_LED2-ALED2VAL
R
0h
These bits are the 24-bit averaged output code for (LED2-
Ambient2) when decimation mode is enabled. The
averaging is done over the number of samples specified
by the decimation factor.
8.5.54 Register 40h (address = 40h) [reset = 0h]
Figure 91. Register 40h
23
15
7
22
14
6
21
13
5
20
19
18
10
2
17
9
16
8
AVG_LED1-ALED1VAL
R-0h
12
11
AVG_LED1-ALED1VAL
R-0h
4
3
1
0
AVG_LED1-ALED1VAL
R-0h
LEGEND: R = Read only; -n = value after reset
Table 78. Register 40h Field Descriptions
Bit
Field
Type
Reset
Description
23-0
AVG_LED1-ALED1VAL
R
0h
These bits are the 24-bit averaged output code for (LED1-
Ambient1) when decimation mode is enabled. The
averaging is done over the number of samples specified
by the decimation factor.
66
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The AFE is designed to operate with a minimal number of external components. Deriving the power supplies for
the AFE from the available source of power in the system can require an additional external LDO or boost
converter. A reset is essential after power-up to ensure that all registers are reset to their default values. TI also
recommends that the entire system be operated using a single master clock. The AFE can either be set to
accept an external clock derived from a master clock generated elsewhere in the system, or the AFE can provide
its internal oscillator as an output clock to serve as the master clock for the rest of the system. If a single master
clock is not possible, extra care must be taken to ensure that spurious energy from unrelated clocks does not get
coupled into the AFE. If this energy does couple into the AFE the spurs get aliased based on the sampling
operation. These aliased spurs can result in a faulty detection of parameters (such as heart rate). The
photodiode outputs are specifically prone to picking up noise. Especially when operating in coexistence and
close proximity with RF communication circuitry [such as Bluetooth® low energy (BLE)], a common-mode choke
may become essential to add in the path of the AFE inputs to reject the interference.
9.2 Typical Application
TX_SUP
LEDs
TX_SUP
RX_SUP
TX1
TX2
TX3
IO_SUP
INP
INM
I2C_CLK
AFE
I2C_DAT
RESETZ
MCU
ADC_RDY
CLK
Rseries
GND
Rshunt
Copyright © 2016, Texas Instruments Incorporated
NOTE: Use Rseries in external clock mode and Rshunt in internal oscillator mode.
Figure 92. Typical AFE Connection
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Typical Application (continued)
Figure 92 illustrates the typical connection of the AFE. The following points are to be noted:
1. Use decoupling capacitors (1 µF or higher) placed close to the device to filter noise on RX_SUP and
TX_SUP.
2. The voltage level used for IO_SUP must be the same as the I/O voltage level for the MCU.
3. In external clock mode, TI recommends connecting a series resistor (Rseries) on the CLK pin. At power-up
and before a RESET pulse is applied, the register bits can be in an uninitialized state. The CLK pin can
possibly be configured as an output pin in this uninitialized state because the CLK pin is an I/O pin. In such a
scenario, Rseries limits the current (because the MCU also attempts to drive the CLK pin). For maximum
frequency of the external clock (60 MHz), the Rseries value is recommended to be 500 Ω.
4. In internal oscillator mode, a shunt resistor (Rshunt) equal to 500 kΩ is recommended to be connected to the
CLK pin. At power-up and after reset, the device resets to the default mode of the external clock. The CLK
pin is in a tri-state mode until the internal clock mode with the CLK output enabled is written through the I2C
interface. The function of Rshunt is to pull down the CLK pin to a logic level of 0 so that the input clock to the
MCU is at a logic level even when the CLK pin is tri-stated.
5. When in power-down mode (PWDN and PDNAFE) the CLK pin must be shut off (tri-stated or driven to zero),
if externally driven.
9.2.1 Design Requirements
The AFE architecture is very flexible, and can be used for both high-performance saturation of peripheral
capillary oxygen (SpO2) applications as well as low-power, battery-operated heart-rate monitoring (HRM)
applications as a result of this flexibility. The high dynamic range of the AFE enables excellent SNR for the signal
of interest (usually small in amplitude) even in the presence of large-signal artifacts resulting from ambient and
motion changes.
9.2.2 Detailed Design Procedure
The following important factors are key to extracting the full performance benefit from the AFE:
1. Good optics including bright LEDs and high-sensitivity photodiodes
2. Good mechanical design
3. A calibration loop that sets the optimal AFE settings based on the signal conditions
TI recommends that a system-level budgeting of dynamic range be initially done based on the following factors:
1. The range of the dc signal currents that are input to the AFE
2. The range of ac-to-dc ratio across different users
3. Signal current changes expected from artifacts (such as motion and ambient light changes)
4. The SNR required for heart-rate extraction algorithms to function successfully
Based on the above analysis, the available dynamic range from the AFE (approximately 100 dB) can be
partitioned between the various components, and the target dc level for the calibration algorithm can also be
arrived at.
9.2.2.1 System-Level ESD Considerations
To meet system-level ESD requirements, additional on-board ESD protection diodes may be required to be
connected to the AFE4404 input pins. The input pins are sensitive to leakage, so using low-leakage ESD diodes
is recommended for protecting these pins.
TI’s portfolio of ESD protection devices can be accessed at the Overview for ESD Protection Diodes page.
The ESD Protection Layout Guide (SLVA680) is available for download at www.ti.com.
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Typical Application (continued)
9.2.2.2 Reducing Sensitivity to Ambient Light Modulation
Ambient light has an additive effect to the LED phase output of the AFE because ambient light occurs on the
photodiode in a manner similar to the light originating from the LED. Any artifacts in ambient light can therefore
interfere with the extraction of the heart rate from the signal in the LED phase. The purpose of subtracting the
ambient phase signal from the LED phase signal is to remove this effect. If the effect of ambient light on the LED
and ambient phase outputs is unequal, then subtraction of the ambient phase data from the LED phase data
gives only an incomplete cancellation of the ambient light modulation effect. In that case, a periodic pattern in the
ambient light can cause spurious tones to appear in the (LED-Ambient) data. The following guidelines can
significantly reduce the sensitivity of the AFE to ambient light modulation:
•
•
Follow the timing guidelines listed in Table 7.
t1 (the start of the LED to the start of sampling) plays a role in the sensitivity to ambient light modulation. For
best performance under high ambient light modulation, keeping t1 to a value greater than 25 µs is
recommended even when operating at low sampling pulse durations.
•
The TIA maintains the photodiode bias through negative feedback. If the TIA output saturates, then the
photodiode bias is disturbed. The associated transient for the photodiode bias to get restored can increase
the sensitivity to ambient light modulation. For example, a saturation of the TIA output during the LED3 phase
can lead to the TIA recovery response to span both the LED1 and Ambient1 phases. This scenario can cause
the channel response to differ between these two phases, thereby rendering the ambient subtraction through
(LED1-Ambient1) to be incomplete. Therefore, the output of every phase is recommended to be prevented
from saturating (through periodic signal monitoring and gain adjustment) even if the data from that phase is
not being used by the heart rate estimation algorithm.
•
If the ambient light changes at a fast rate, the effective ambient signal observed during the LED and ambient
phases can be different because of the difference between the sampling instants. This effect can also cause
the ambient subtraction to be incomplete. Reducing the spacing between the sampling instants of the LED
and ambient can reduce this effect.
Figure 93 is the AFE output in the ambient phase resulting from modulation applied to the ambient light.
Figure 94 is the (LED-Ambient) phase data with non-optimal settings and Figure 95 is the (LED-Ambient) phase
data with optimal settings.
452000
451000
450000
449000
448000
447000
446000
445000
444000
443000
442000
441000
440000
90000
80000
70000
60000
50000
40000
30000
20000
10000
0
-10000
0
200
400
600
800
1000
0
200
400
600
800
1000
Sample Number
Sample Number
Figure 93. Ambient Data with Ambient Light Modulation
Figure 94. (LED-Ambient) Data with a Non-Optimal AFE
Setting
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Typical Application (continued)
447000
446000
445000
444000
443000
442000
441000
440000
439000
438000
437000
436000
435000
0
200
400
600
800
1000
Sample Number
Figure 95. (LED-Ambient) Data with an Optimal AFE Setting
9.2.3 Application Curves
This section outlines the trends described in the Typical Characteristics section from an application perspective.
Figure 1 illustrates the receiver current across different external clock frequencies. Each of the curves
corresponds to a different CLKDIV_EXTMODE setting that determines the division ratio between the external
clock and the internal clock (CLK_INT). The internal clock frequency must be in the range of 4 MHz to 6 MHz for
proper operation, and each curve corresponds to a sweep of the external clock frequency that corresponds to an
internal clock frequency sweep over the range of 4 MHz to 6 MHz.
Figure 2 illustrates the receiver current across the PRF with the dynamic power-down signal (PDN_CYCLE)
enabled during the portion of the period when the receiver does not need to be active. The active period is
maintained as 500 µs for each PRF setting and the device is in power-down mode (set by PDN_CYCLE) for the
rest of the period. Additionally, the timing margins indicated as t8 and t9 in Figure 35 are included before and
after the PDN_CYCLE pulse. The fraction of time that the device is in power-down mode over a period increases
with reduction in the PRF because the period scales inversely with PRF. This timing is the reason why the curve
displays a reduction in the average receiver current with reduction in PRF. The curve corresponding to
CLKDIV_PRF = 1 terminates at a lower PRF of approximately 61 Hz, which is determined by the maximum
range of the 16-bit timing counter (4 MHz divided by 216). With the CLKDIV_PRF set to 16, the timer clock is
divided by 16. Thus, the lower PRF range can be extended down to a few hertz (the recommended operation is
to restrict the range to 10 Hz or higher). For the same PRF (for example 100 Hz), a higher CLKDIV_PRF setting
results in a lower power consumption because the timer engine runs on a slower clock and takes less switching
current.
The noise plots from Figure 3 to Figure 7 are taken at a PRF of 100 Hz. For this PRF setting, the noise at the
output of the AFE is distributed from 0 Hz to 50 Hz. Plots that indicate the noise as over Nyquist bandwidth have
integrated noise from 1 Hz to 50 Hz. The plots that indicate the noise as over 20-Hz bandwidth have integrated
noise until 20 Hz. These plots are suitable for when additional low-pass filtering is implemented in the MCU to
limit the noise bandwidth (in this case, to 20 Hz). This low-pass filtering can improve SNR because the PPG
signal has information contained in the frequency band below 10 Hz.
Figure 3 illustrates the input-referred noise current versus sampling duration duty cycle for different voltage levels
at the receiver output. The PPG signal has a dc component that can cause the signal at the output of the
receiver to be anywhere between ±FS (full-scale). The curves in Figure 3 illustrate a slight increase in the noise
around higher dc levels, which results from additional noise sources in the ADC. The input-referred noise current
can be visualized as a noise current flowing into one of the input pins (for instance, INP) and flowing out of the
other (for example, INM). The noise is computed on the samples that constitute the difference between the LED
phase and the ambient phase.
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Typical Application (continued)
Figure 4 illustrates the SNR plots corresponding to the same data as Figure 3. The input-referred noise and SNR
can be related as follows: the input-referred noise current can be first referred to the receiver output using a
factor of 2Rf, where Rf is 500 kΩ for this case. This output-referred voltage gives the output noise that can then
be referred to the full-scale value of 2 V (note that when the full-scale differential input to the ADC is 2.4 VPP, the
operating range is 2 VPP, which is the valid operating range of the TIA).
Figure 5 plots the input-referred noise current versus sampling duty cycle across different TIA gain settings.
Figure 6 corresponds to the SNR plot of the data in Figure 5. As illustrated in Figure 5, a dynamic range of 100
dB or more can be achieved in the receiver for many of the TIA gain settings. A reduction in SNR for higher TIA
gain settings is in line with what is expected from the receiver because a higher TIA gain setting implies a lower
signal level at the input of the receiver.
Figure 7 and Figure 8 correspond to the input-referred noise current and corresponding SNR across the
sampling duration duty cycle for different settings of the ADC averaging (as set by the NUMAV register setting).
An ADC averaging of 1 implies no averaging. As illustrated in these curves, the SNR improves with averaging
more samples. This improvement becomes more pronounced at lower TIA gain settings where the ADC noise
has a higher affect on the overall receiver noise.
The input-referred current noise current versus sampling duty cycle for different decimation factors is illustrated in
Figure 9. As illustrated in Figure 9, a 4X decimation leads to almost a 2X reduction in input-referred noise.
Figure 10 refers to a hypothetical case that is used to illustrate the improvement in the receiver dynamic range
when using the offset cancellation DAC. Assume that the dc level of the signal current corresponds to 7.25 µA.
Without the offset cancellation DAC, assume operation is with a TIA gain of 25 kΩ, which causes the output of
the receiver to be at 362.5 mV. If the offset cancellation DAC is enabled with a subtraction current of 7 µA (the
maximum setting), then the signal level at the input of the TIA after the offset cancellation DAC subtraction is
0.25 µA. For this current, a TIA gain setting of 1 MΩ causes the TIA output to be at 500 mV. In effect, by
enabling the offset cancellation DAC with the right setting, a higher TIA gain setting is allowed, which ends up
reducing the contribution of the ADC noise and thereby reduces the input-referred noise current of the receiver.
Note that the benefit from the offset cancellation DAC may not be so dramatic in an actual use case because
perfect cancellation of the dc signal may not be achieved from the 0.5-µA resolution of the offset cancellation
DAC. Even if achieved, the highest possible TIA gain setting on the residual current may cause receiver
saturation with small changes in the dc signal level. For this reason, a safe value for the maximum gain setting
when operating with the offset cancellation DAC is 250 kΩ or less. The third curve in Figure 10 illustrates this
case.
Figure 11 illustrates the effective response of the switched RC filter at the receiver output. The switched RC filter
has a physical RC time constant that corresponds to a bandwidth of approximately 2.5 kHz. However, the
effective bandwidth of the filter scales approximately with the sampling duration duty cycle. For a lower duty
cycle, the effective filter bandwidth reduces as described from the comparison of a 5% duty cycle with a 25%
duty cycle. At even lower duty cycles, the filter can double-up as a noise bandwidth reduction filter that can relax
the digital-filtering requirements in the MCU.
Figure 12 illustrates the switched RC filter response for a sampling duty cycle of 1% across different PRF
settings.
Figure 13 illustrates the switched RC filter response for a sampling duty cycle of 5% across different PRF
settings.
Figure 14 illustrates the LED current value versus the LED current setting code. The mode marked as 50-mA
LED Current Mode corresponds to the default setting of ILED_2X = 0, whereas the mode marked as 100-mA
LED Current Mode corresponds to ILED_2X = 1. The ideal slope of these curves corresponds to 0.793 mA per
code for the 50-mA current mode and 1.587 mA per code for the 100-mA current mode. However, a small
deviation from these ideal values can exist from device to device, and can be viewed as a gain error in the LED
current versus code. This deviation can be larger for the 100-mA current mode, with slight saturation of current
especially at the high-current settings.
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Typical Application (continued)
Figure 15 illustrates the LED current as a function of the voltage at the TX pin. The voltage at the TX pin is
changed by connecting a load resistor from the TX pin to TX_SUP and changing the voltage of TX_SUP. In the
50-mA current mode, with a 50-mA current setting, the LED current starts to drop when the voltage at the TX pin
goes below 0.5 V. In the 100-mA current mode, with a 100-mA current setting, the current starts to drop when
the voltage at the TX pin goes below 1 V.
Figure 16 and Figure 17 illustrate the LED current step error as a function of the LED current setting code for the
50-mA and 100-mA current modes. These plots are generated from the data in Figure 14 after removing the gain
error component (based on the best-fit curve).
Figure 18 illustrates the power-supply rejection ratio (PSRR) for a tone on the TX_SUP power rail. The frequency
of the tone is swept and the magnitude of the same tone at the device output (LED-ambient) is monitored. Note
that in cases where the tone frequency is greater than PRF / 2, power is monitored at the aliasing frequency.
PSRR is computed as the RMS value of the output tone referred to the RMS value of the tone applied on the
supply pin.
Figure 19 illustrates the PSRR for a tone applied on the RX_SUP power rail. PSRR is enhanced because of the
presence of an internal LDO that drives the signal chain as well as the differential nature of the signal chain.
Figure 20 illustrates the rejection of a 50-Hz differential input tone. A differential current input with a frequency of
50 Hz is applied on the input pins. The magnitude of the tone at the output of the device (LED minus ambient
phase) is converted to an input-referred current and compared with the magnitude of the injected current to
estimate the rejection. The rejection is plotted as a function of the separation between the sampling instants of
the LED and ambient phases. As illustrated in Figure 20, with reducing separation between the sampling
instants, the rejection keeps improving because of an increased correlation of the injected tone between the two
phases. A similar rejection is not obtained if only the LED phase data are considered.
Figure 21 illustrates the SNR in dBFS over a 20-Hz bandwidth across sampling duty cycle over multiple
operating temperatures ranging from –40°C to 85°C.
Figure 22 illustrates the variation of the internal oscillator frequency over operating temperature on a typical unit.
9.2.3.1 Choosing the Right AFE Settings
The AFE signal chain offers several knobs that can be adjusted to achieve the SNR requirements needed for
high-end, clinical, pulse-oximeter applications as well as for the low-power demands of battery-operated, optical,
heart-rate monitoring applications. The knobs include TIA gain (Rf), TIA bandwidth, LED current (ILED), and
offset cancellation DAC (I_OFFDAC). TI highly recommends running a calibration algorithm at startup and also
periodically on the MCU to monitor the dc level at the output of the AFE and adjust the AFE signal chain settings
to get close to the target dc level.
In addition to a target dc level, the high and low thresholds can also be determined (for example, 80% and 20%
of full-scale), which can cause the algorithm to switch to a different TIA gain or LED current setting when the
signal amplitude changes beyond the thresholds.
The optimum gain and LED current depends on the following conditions:
1. The current transfer ratio (CTR) from the LED to the photodiode
2. The perfusion index at the ADC output (the ac to dc ratio of the signal)
For clinical SPO2 applications demanding the highest SNR, where power may not be a primary concern, TI
recommends setting the LED and sampling pulse durations to > 200 µs. To simplify system design, keeping the
pulse duration fixed across use cases is easiest. Set the LED current to the highest value that can be afforded by
the system power budget. Initialize the TIA gain to the lowest gain setting of 10 kΩ and use the initial calibration
routine to determine the optimum gain. Set the ADC in averaging mode with the number of averages being the
maximum afforded by the choice of pulse repetition period and pulse duration. Eight ADC averages is usually
sufficient to obtain good SNR.
For power-critical, battery-operated applications, choose a sampling pulse duration between 50 µs to 100 µs and
operate the device at a high TIA gain setting (for example, 1 MΩ). Set the ADC in averaging mode with four to
eight averages. Initialize the LED current to the desired lowest setting (of a few milliamps) and use the initial
calibration routine to determine the optimum LED current setting up to the highest value allowed by the system
power budget.
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Typical Application (continued)
For pulse-oximeter applications using red and IR LEDs, the target dc level can be typically set to 50% of positive
full-scale.
For HRM applications, the offset cancellation DAC can be additionally used such that the dc offset can be
subtracted from the signal, thereby allowing for a larger TIA gain to be applied without saturating the signal.
The calibration routine must be designed in a manner that does not rely on the accuracy of the LED current, TIA
gain, and offset cancellation DAC, thus allowing for device-to-device variations. Specifically, the offset
cancellation DAC is not trimmed at production and can have a significant device-to-device variation (±20%). If the
calibration routine requires an accurate estimate of the offset cancellation DAC, then the PD_DISCONNECT
mode can be used to estimate the offset cancellation DAC range on a given unit. The PD_DISCONNECT mode
disconnects the photodiode from the TIA inputs. In this mode IPD = 0 and, thus, the effective input current to the
TIA comes solely from the offset cancellation DAC (Ieff = I_OFFDAC). As a result, the offset cancellation DAC
value can be directly estimated from the AFE output code.
When the calibration loop is in the process of converging to the steady state, the device settings can continue to
be refreshed to new values. Ideally, a time equal to tCHANNEL is provided for the AFE to settle to any change in
signal-chain settings. However, this time can lead to unacceptably large delays in the convergence of the
calibration routine. Therefore, during the transient (when the calibration routine is in the transient phase), the wait
times can be reduced to as low as tCHANNEL / 10. After the calibration routine converges to the final settings, a
wait time of tCHANNEL can then be applied before high-accuracy data are read out from the AFE.
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10 Power Supply Recommendations
The guidelines for power-supply sequencing and device initialization are shown in Figure 96, Figure 97, and
Table 79.
RX_SUP
t1
IO_SUP
t2
TX_SUP
t3
RESETZ
t4
t5
t6
t7
t4
t5
t6
Device
Settings
Device
Settings
I2C Interface
ADC_RDY
t8
CLK
(External Clock Mode)
High-Accuracy
Operation
Hardware
Power-
Down
High-Accuracy Operation
Reset
Device State
(PWDN)
Figure 96. Power-Supply Sequencing, Device Initialization, and Hardware Power-Down Timing
RX_SUP
t1
IO_SUP
t2
TX_SUP
t3
RESETZ
t4
t5
t6
t6
Device
Settings
PDNAFE
= 1
PDNAFE
= 0
I2C Interface
ADC_RDY
CLK
(External Clock Mode)
High-Accuracy
Operation
High-Accuracy Operation
Software Power-Down (PDNAFE)
Device State
Figure 97. Power-Supply Sequencing, Device Initialization, and Software Power-Down Timing
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Table 79. Timing Parameters for Power Supply Sequencing, Device Initialization, and Power-Down
Timing
VALUE
Ramp up RX_SUP before or at the same time as IO_SUP. Keep t1 as
Time between RX_SUP and IO_SUP ramping up
t1
t2
t3
small as possible (for example,10 ms).
Time between RX_SUP and TX_SUP ramping up
Keep t2 as small as possible (for example,10 ms).
> 10 ms
Time between all supplies stabilizing and start of the RESETZ low-
going pulse
t4
t5
RESETZ pulse duration for the device to get reset
Between 25 µs and 50 µs
> 1 ms
Time between resetting the device and issuing of I2C commands
Time between I2C commands and the ADC_RDY pulse that
corresponds to valid data
(1)
t6
t7
t8
tCHANNEL
RESETZ pulse duration for the device to enter PWDN (power-down)
mode
> 200 µs
> 10 ms
Time from exiting power-down mode and subsequently resetting the
device
(1) The tCHANNEL parameter is specified in the Electrical Characteristics table.
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11 Layout
11.1 Layout Guidelines
Two key layout guidelines are:
1. TX1, TX2, and TX3 are fast-switching lines and must be routed away from sensitive lines (such as the INP,
INN inputs).
2. The device can draw high-switching currents from the TX_SUP pin. A decoupling capacitor must be
electrically close to the pin.
11.2 Layout Example
Figure 98. Example Layout
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12 器件和文档支持
12.1 社区资源
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.2 商标
E2E is a trademark of Texas Instruments.
Bluetooth is a registered trademark of Bluetooth SIG, Inc.
All other trademarks are the property of their respective owners.
12.3 静电放电警告
ESD 可能会损坏该集成电路。德州仪器 (TI) 建议通过适当的预防措施处理所有集成电路。如果不遵守正确的处理措施和安装程序 , 可
能会损坏集成电路。
ESD 的损坏小至导致微小的性能降级 , 大至整个器件故障。 精密的集成电路可能更容易受到损坏 , 这是因为非常细微的参数更改都可
能会导致器件与其发布的规格不相符。
12.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
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13 机械、封装和可订购信息
以下页中包括机械、封装和可订购信息。这些信息是针对指定器件可提供的最新数据。这些数据会在无通知且不对
本文档进行修订的情况下发生改变。欲获得该数据表的浏览器版本，请查阅左侧的导航栏
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YZP0015
DSBGA - 0.5 mm max height
SCALE 7.000
DIE SIZE BALL GRID ARRAY
A
B
E
BALL A1
CORNER
E = 1.6 mm
D = 2.6 mm
D
C
0.5 MAX
SEATING PLANE
0.05 C
0.19
0.13
BALL TYP
1 TYP
0.5 TYP
E
D
SYMM
2
C
B
TYP
0.5
TYP
A
1
2
3
0.25
0.21
15X
C A
SYMM
0.015
B
4221665/A 09/2014
NanoFree Is a trademark of Texas Instruments.
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. NanoFreeTM package configuration.
图 99. 封装外形
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EXAMPLE BOARD LAYOUT
YZP0015
DSBGA - 0.5 mm max height
DIE SIZE BALL GRID ARRAY
(0.5) TYP
15X (
0.23)
3
1
2
A
(0.5) TYP
B
SYMM
C
D
E
SYMM
LAND PATTERN EXAMPLE
SCALE:30X
0.05 MAX
0.05 MIN
( 0.23)
METAL
METAL
UNDER
SOLDER MASK
(
0.23)
SOLDER MASK
OPENING
SOLDER MASK
OPENING
NON-SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK
DEFINED
SOLDER MASK DETAILS
NOT TO SCALE
4221665/A 09/2014
NOTES: (continued)
4. Final dimensions may vary due to manufacturing tolerance considerations and also routing constraints.
For more information, see Texas Instruments literature number SBVA017 (www.ti.com/lit/sbva017).
图 100. 电路板布局示例
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EXAMPLE STENCIL DESIGN
YZP0015
DSBGA - 0.5 mm max height
DIE SIZE BALL GRID ARRAY
(0.5) TYP
(R0.05) TYP
15X ( 0.25)
1
3
2
A
B
C
(0.5)
TYP
METAL
TYP
SYMM
D
E
SYMM
SOLDER PASTE EXAMPLE
BASED ON 0.1 mm THICK STENCIL
SCALE:40X
4221665/A 09/2014
NOTES: (continued)
5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release.
图 101. 模板设计示例
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81
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JESD48 最新标准中止提供任何产品和服务。客户在下订单前应获取最新的相关信息, 并验证这些信息是否完整且是最新的。所有产品的销售
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用测试或其它质量控制技术。除非适用法律做出了硬性规定，否则没有必要对每种组件的所有参数进行测试。
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Copyright © 2016, 德州仪器半导体技术（上海）有限公司
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
Samples
Drawing
Qty
(1)
(2)
(3)
(4/5)
(6)
AFE4404YZPR
AFE4404YZPT
ACTIVE
ACTIVE
DSBGA
DSBGA
YZP
YZP
15
15
3000 RoHS & Green
250 RoHS & Green
SNAGCU
Level-1-260C-UNLIM
Level-1-260C-UNLIM
-20 to 70
-20 to 70
AFE4404
AFE4404
SNAGCU
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
14-Jun-2016
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
AFE4404YZPR
AFE4404YZPT
DSBGA
DSBGA
YZP
YZP
15
15
3000
250
180.0
180.0
8.4
8.4
1.68
1.68
2.68
2.68
0.59
0.59
4.0
4.0
8.0
8.0
Q1
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
14-Jun-2016
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
AFE4404YZPR
AFE4404YZPT
DSBGA
DSBGA
YZP
YZP
15
15
3000
250
182.0
182.0
182.0
182.0
20.0
20.0
Pack Materials-Page 2
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