CS5571-ISZ [CIRRUS]
【2.5 V / 5 V, 100 kSps, 16-bit, High-throughput ツヒ ADC; 【 2.5 V / 5 V ， 100 kSPS时， 16位，高通量ツヒADC
| 型号： | CS5571-ISZ |
| 厂家： | 
CIRRUS LOGIC |
| 描述： | 【2.5 V / 5 V, 100 kSps, 16-bit, High-throughput ツヒ ADC |
| 文件： | 总32页 (文件大小：595K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
6/25/07
14:12
CS5571
±2.5 V / 5 V, 100 kSps, 16-bit, High-throughput ∆Σ ADC
Features & Description
General Description
The CS5571 is a single-channel, 16-bit analog-to-digital
converter capable of 100 kSps conversion rate. The input
accepts a single-ended analog input signal. On-chip buff-
ers provide high input impedance for both the AIN input
and the VREF+ input. This significantly reduces the drive
requirements of signal sources and reduces errors due to
source impedances. The CS5571 is a delta-sigma convert-
er capable of switching multiple input channels at a high
rate with no loss in throughput. The ADC uses a low-laten-
cy digital filter architecture. The filter is designed for fast
settling and settles to full accuracy in one conversion. The
converter's 16-bit data output is in serial format, with the
serial port acting as either a master or a slave. The convert-
er is designed to support bipolar, ground-referenced
signals when operated from ±2.5V analog supplies.
Single-ended Analog Input
On-chip Buffers for High Input Impedance
Conversion Time = 10 µS
Settles in One Conversion
Linearity Error = 0.0007%
Signal-to-Noise = 92 dB
S/(N + D) = 91 dB
DNL = ±0.1 LSB Max.
Self-calibration:
- Maintains accuracy over time & temperature.
Simple three/four-wire serial interface
The CS5571 uses self-calibration to achieve low offset and
gain errors. The converter achieves a S/N of 92 dB. Linear-
ity is 0.0007% of full scale.
Power Supply Configurations:
- Analog: +5V/GND; IO: +1.8V to +3.3V
- Analog: ±2.5V; IO: +1.8V to +3.3V
The converter can operate from an analog supply of 0-5V
or from ±2.5V. The digital interface supports standard logic
operating from 1.8, 2.5, or 3.3 V.
Power Consumption:
- ADC Input Buffers On: 85 mW
- ADC Input Buffers Off: 60 mW
ORDERING INFORMATION:
See Ordering Information on page 31.
V1+
V2+
VL
CS5571
VREF+
VREF-
SMODE
CS
SERIAL
INTERFACE
DIGITAL
FILTER
LOGIC
SCLK
ADC
AIN
SDO
RDY
ACOM
DITHER
RST
CONV
BUFEN
CALIBRATION
MICROCONTROLLER
CAL
OSC/CLOCK
BP/UP
GENERATOR
MCLK
V2-
TST
VLR
V1-
DCR
This document contains information for a new product.
Cirrus Logic reserves the right to modify this product without notice.
Advance Product Information
JUN ‘07
DS768A5
Copyright © Cirrus Logic, Inc. 2007
http://www.cirrus.com
(All Rights Reserved)
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CS5571
TABLE OF CONTENTS
1. CHARACTERISTICS AND SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
ANALOG CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
SWITCHING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
DIGITAL CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
DIGITAL FILTER CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
GUARANTEED LOGIC LEVELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
RECOMMENDED OPERATING CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2. OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3. THEORY OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Reset and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Performing Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3 Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4 Voltage Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5 Analog Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.6 Output Coding Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.7 Typical Connection Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.8 AIN & VREF Sampling Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.9 Converter Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.10 Digital Filter Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
3.11 Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.11.1 SSC Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.11.2 SEC Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.12 Power Supplies & Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.13 Using the CS5571 in Multiplexing Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.14 Synchronizing Multiple Converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4. PIN DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5. PACKAGE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6. ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7. ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION . . . . . . . . . . . . . . 31
8. REVISION HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
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CS5571
LIST OF FIGURES
Figure 1. SSC Mode - Read Timing, CS remaining low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 2. SSC Mode - Read Timing, CS falling after RDY falls . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3. SEC Mode - Read Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 4. Voltage Reference Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 5. CS5571 Configured Using ±2.5V Analog Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 6. CS5571 Configured for Unipolar Measurement Using a Single 5V Analog Supply. . . . 18
Figure 7. CS5571 Configured for Bipolar Measurement Using a Single 5V Analog Supply . . . . . 19
Figure 8. CS5571 DNL Plot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 9. CS5571 DNL Histogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 10. CS5571 Small Signal Performance (Dither On). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 11. CS5571 Small Signal Performance (Dither Off). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 12. CS5571 Spectral Response (DC to fs/2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 13. CS5571 Spectral Response (DC to 10 kHz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 14. CS5571 Spectral Response (DC to 4fs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 15. Simple Multiplexing Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 16. More Complex Multiplexing Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
LIST OF TABLES
Table 1. Output Coding, Two’s Complement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 2. Output Coding, Offset Binary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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CS5571
1. CHARACTERISTICS AND SPECIFICATIONS
•
•
•
Min / Max characteristics and specifications are guaranteed over the specified operating conditions.
Typical characteristics and specifications are measured at nominal supply voltages and T = 25°C.
A
VLR = 0 V. All voltages measured with respect to 0 V.
ANALOG CHARACTERISTICS T = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- = V2- = -2.5 V,
A
±5%; VL -VLR = 3.3 V, ±5%; VREF = (VREF+) - (VREF-) = 4.096V; MCLK = 16 MHz; SMODE = VL. DITHER = VL
unless otherwise stated; BUFEN = V1+ unless otherwise stated. Connected per Figure 5. Bipolar mode unless oth-
erwise stated.
Parameter
Min
Typ
Max
Unit
Accuracy
Linearity Error
(Note 1)
-
-
0.0007
-
-
%FS
Differential Linearity Error
(Note 2)
±0.1
LSB
16
Positive Full-scale Error
After Reset
After Calibration (Note 1)
-
-
1.0
1.0
±1
-
-
-
%FS
LSB
16
Negative Full-scale Error
After Reset
After Calibration (Note 1)
-
-
%FS
LSB
16
Full-scale Drift
Unipolar Offset
(Note 3)
(Note 3)
-
LSB
16
After Reset
After Calibration (Note 1)
-
-
-
-
LSB
LSB
16
16
Unipolar Offset Drift
Bipolar Offset
-
±2
-
LSB
16
After Reset
After Calibration (Note 1)
-
-
-
-
LSB
LSB
16
16
Bipolar Offset Drift
(Note 3)
(Note 4)
-
-
±1
36
-
-
LSB
16
Noise
µVrms
Dynamic Performance
Peak Harmonic or Spurious Noise
1 kHz, -0.5 dB Input
12 kHz, -0.5 dB Input
-
-
-110
-110
-
-
dB
dB
Total Harmonic Distortion
Signal-to-Noise
1 kHz, -0.5 dB Input
-
-
-102
92
-
-
dB
dB
S/(N + D) Ratio
-0.5 dB Input, 1 kHz
-60 dB Input, 1 kHz
-
-
91
32
-
-
dB
dB
-3 dB Input Bandwidth
(Note 5)
-
84
-
kHz
1. Applies after calibration at any temperature within -40 °C to +85 °C.
2. No missing codes is guaranteed at 16 bits resolution over the specified temperature range.
3. Total drift over specified temperature range after calibration at power-up, at 25º C.
4. With DITHER off the output will be dominated by quantization.
5. Scales with MCLK.
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CS5571
ANALOG CHARACTERISTICS (CONTINUED) T = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- =
A
V2- = -2.5 V, ±5%; VL -VLR = 3.3 V, ±5%; VREF = (VREF+) - (VREF-) = 4.096V; MCLK = 16 MHz; SMODE = VL.
DITHER = VL unless otherwise stated; BUFEN = V1+ unless otherwise stated. Connected per Figure 5.
Parameter
Min
Typ
Max
Unit
Analog Input
Analog Input Range
Unipolar
Bipolar
0 to +VREF / 2
±VREF / 2
V
V
Input Capacitance
-
10
-
pF
CVF Current (Note 6)
AIN Buffer On (BUFEN = V+)
AIN Buffer Off (BUFEN = V-)
ACOM
-
-
-
600
130
130
-
-
-
nA
µA
µA
Voltage Reference Input
Voltage Reference Input Range
(VREF+) – (VREF-)
4.2
-
(Note 7)
2.4
-
4.096
10
V
Input Capacitance
CVF Current
pF
VREF+ Buffer On (BUFEN = V+)
VREF+ Buffer Off (BUFEN = V-)
VREF-
-
-
-
3
1
1
-
-
-
µA
mA
mA
Power Supplies
DC Power Supply Currents
I
I
I
-
-
-
-
-
-
18
1.8
0.5
mA
mA
mA
V1
V2
VL
Power Consumption
Normal Operation Buffers On
Buffers Off
-
-
85
60
105
90
mW
mW
Power Supply Rejection
(Note 8) V1+ , V2+ Supplies
V1-, V2- Supplies
90
90
110
110
-
-
dB
dB
6. Measured using an input signal of 1 V DC.
7. For optimum performance, VREF+ should always be less than (V+) - 0.2 volts to prevent saturation of the VREF+ input buffer.
8. Tested with 100 mVP-P on any supply up to 1 kHz. V1+ and V2+ supplies at the same voltage potential, V1- and V2- supplies at
the same voltage potential.
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CS5571
SWITCHING CHARACTERISTICS
T = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- = V2- = -2.5 V, ±5%;
A
VL - VLR = 3.3 V, ±5%, 2.5 V, ±5%, or 1.8 V, ±5%
Input levels: Logic 0 = 0V; Logic 1 = VD+; CL = 15 pF.
Parameter
Symbol
Min
Typ
Max
Unit
Master Clock Frequency
Internal Oscillator
External Clock
XIN
12
0.5
14
16
16
16.2
MHz
MHz
f
clk
Master Clock Duty Cycle
Reset
40
-
60
%
RST Low Time
(Note 9)
t
1
-
-
µs
res
RST rising to RDY falling
Internal Oscillator
External Clock
t
-
-
120
1536
-
-
µs
MCLKs
wup
Calibration
CAL pulse width
(Note 10, 11)
(Note 10, 11)
t
4
0
-
-
-
-
MCLKs
ns
pw
CAL high setup time to RST rising
t
ccw
Calibration Time
t
scl
RST rising (CAL high) to RDY falling
-
-
167298
167298
-
-
MCLKs
MCLKs
Calibration Time
CAL rising (RST high) to RDY falling
t
cal
Conversion
CONV Pulse Width
t
4
0
-
-
-
-
-
-
MCLKs
ns
cpw
BP/UP setup to CONV falling
(Note 12)
t
scn
scn
bus
CONV low to start of conversion
t
-
2
-
MCLKs
MCLKs
Perform Single Conversion (CONV high before RDY falling)
t
20
Conversion Time
(Note 13)
Start of Conversion to RDY falling
t
-
-
164
MCLKs
buh
9. Reset must not be released until the power supplies and the voltage reference are within specification.
10. CAL must remain high until RDY falls at the end of the calibration time.
11. CAL can be controlled by the same signal used for RST. If CAL goes high simultaneously with RST, a calibration
will be performed. CAL must remain high until RDY falls.
12. BP/UP can be changed coincident CONV falling. BP/UP must remain stable until RDY falls.
13. If CONV is held low continuously, conversions occur every 160 MCLK cycles.
If RDY is tied to CONV, conversions will occur every 162 MCLKs.
If CONV is operated asynchronously to MCLK, a conversion may take up to 164 MCLKs.
RDY falls at the end of conversion.
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CS5571
SWITCHING CHARACTERISTICS (CONTINUED)
T = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- = V2- = -2.5 V, ±5%;
A
VL - VLR = 3.3 V, ±5%, 2.5 V, ±5%, or 1.8 V, ±5%
Input levels: Logic 0 = 0V; Logic 1 = VD+; CL = 15 pF.
Parameter
Serial Port Timing in SSC Mode (SMODE = VL)
RDY falling to MSB stable
Symbol
Min
Typ
Max
Unit
t
t
-
-
-2
-
-
MCLKs
ns
1
2
Data hold time after SCLK rising
10
Serial Clock (Out)
(Note 14, 15)
Pulse Width (low)
Pulse Width (high)
t
t
50
50
-
-
-
-
ns
ns
3
4
RDY rising after last SCLK rising
t
-
8
-
MCLKs
5
14. SDO and SCLK will be high impedance when CS is high. In some systems it may require a pull-down resister.
15. SCLK = MCLK/2.
MCLK
RDY
t5
t1
CS
t3
t4
t2
SCLK(o)
LSB
LSB+1
SDO
MSB
MSB–1
Figure 1. SSC Mode - Read Timing, CS remaining low (Not to Scale)
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SWITCHING CHARACTERISTICS (CONTINUED)
T = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- = V2- = -2.5 V, ±5%;
A
VL - VLR = 3.3 V, ±5%, 2.5 V, ±5%, or 1.8 V, ±5%
Input levels: Logic 0 = 0V; Logic 1 = VD+; CL = 15 pF.
Parameter
Serial Port Timing in SSC Mode (SMODE = VL)
Data hold time after SCLK rising
Symbol
Min
Typ
Max
Unit
t
-
10
-
ns
7
Serial Clock (Out)
(Note 16, 17)
Pulse Width (low)
Pulse Width (high)
t
t
50
50
-
-
-
-
ns
ns
8
9
RDY rising after last SCLK rising
CS falling to MSB stable
t
-
-
8
10
8
-
-
-
-
-
MCLKs
ns
10
t
11
12
13
14
First SCLK rising after CS falling
CS hold time (low) after SCLK rising
SCLK, SDO tri-state after CS rising
t
t
t
-
MCLKs
ns
10
-
-
5
ns
16. SDO and SCLK will be high impedance when CS is high. In some systems it may require a pull-down resister.
17. SCLK = MCLK/2.
MCLK
t10
RDY
t13
CS
t8
t9
t14
t12
t7
SCLK(o)
t11
LSB
LSB+1
MSB
MSB–1
SDO
Figure 2. SSC Mode - Read Timing, CS falling after RDY falls (Not to Scale)
8
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SWITCHING CHARACTERISTICS (CONTINUED)
T = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- = V2- = -2.5 V, ±5%;
A
VL - VLR = 3.3 V, ±5%, 2.5 V, ±5%, or 1.8 V, ±5%
Input levels: Logic 0 = 0V; Logic 1 = VD+; CL = 15 pF.
Parameter
Serial Port Timing in SEC Mode (SMODE = VLR)
SCLK(in) Pulse Width (High)
Symbol
Min
Typ
Max
Unit
-
-
30
30
10
-
-
-
-
-
-
ns
ns
ns
SCLK(in) Pulse Width (Low)
CS hold time (high) after RDY falling
t
t
t
t
t
t
t
15
16
17
18
19
20
21
CS hold time (high) after SCLK rising
CS low to SDO out of Hi-Z
10
-
-
10
10
-
-
-
-
-
-
-
ns
ns
ns
ns
ns
ns
(Note 18)
Data hold time after SCLK rising
Data setup time before SCLK rising
CS hold time (low) after SCLK rising
RDY rising after SCLK falling
-
10
10
-
-
10
18. SDO will be high impedance when CS is high. In some systems it may require a pull-down resister.
MCLK
t21
RDY
CS
t15
t20
t16
SCLK(i)
SDO
t17
t18
t19
MSB
LSB
Figure 3. SEC Mode - Read Timing (Not to Scale)
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DIGITAL CHARACTERISTICS
TA = TMIN to TMAX; VL = 3.3V, ±5% or VL = 2.5V, ±5% or 1.8V, ±5%; VLR = 0V
Parameter
Calibration Memory Retention
Symbol
Min
Typ
Max
Unit
(Note 19)
Power Supply Voltage [V1+ = V2+] – [V1- = V2-]
VMR
Iin
4.0
-
-
-
2
-
V
Input Leakage Current
-
-
-
µA
pF
pF
Digital Input Pin Capacitance
Cin
3
3
Digital Output Pin Capacitance
Cout
-
19. V1- and V2- can be any value from 0 to +5V for memory retention. Neither V1- nor V2- should be allowed to go positive. AIN1,
AIN2, or VREF must not be greater than V1+ or V2+. This parameter is guaranteed by characterization.
DIGITAL FILTER CHARACTERISTICS
TA = TMIN to TMAX; VL = 3.3V, ±5% or VL = 2.5V, ±5% or 1.8V, ±5%; VLR = 0V
Parameter
Symbol
Min
Typ
Max
Unit
Group Delay
-
-
160
-
MCLKs
10
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CS5571
GUARANTEED LOGIC LEVELS
TA = -40 to +85 °C; V1+ = V2+ = +2.5 V, ±5%; V1- = V2- = -2.5 V, ±5%;
VL - VLR = 3.3 V, ±5%, 2.5 V, ±5%, or 1.8 V, ±5%
Input levels: Logic 0 = 0V; Logic 1 = VL; CL = 15 pF.
Guaranteed Limits
Parameter
Sym
VIH
VL
Min
Typ
Max
Unit
V
Conditions
Logic Inputs
3.3
2.5
1.8
3.3
2.5
1.8
1.9
1.6
1.2
Minimum High-level Input Voltage:
Maximum Low-level Input Voltage:
1.1
0.95
0.6
VIL
V
Logic Outputs
3.3
2.5
1.8
3.3
2.5
1.8
2.9
2.1
Minimum High-level Output Voltage:
Maximum Low-level Output Voltage:
IOH = -2 mA
IOH = -2 mA
VOH
V
V
1.65
0.36
0.36
0.44
VOL
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CS5571
RECOMMENDED OPERATING CONDITIONS
(VLR = 0V, see Note 20)
Parameter
Symbol
Min
Typ
Max
Unit
Single Analog Supply
DC Power Supplies:
(Note 20)
V1+
V1+
V2-
V1+
V2-
4.75
4.75
-
-
5.0
5.0
0
5.25
5.25
-
-
V
V
V
V
V2+
V1-
V2-
0
Dual Analog Supplies
DC Power Supplies:
(Note 20)
V1+
V1+
V2-
V1+
V2-
+2.375
+2.375
-2.375
-2.375
+2.5
+2.5
-2.5
-2.5
+2.625
+2.625
-2.625
-2.625
V
V
V
V
V2+
V1-
V2-
Analog Reference Voltage
(Note 21)
VREF
2.4
4.096
4.2
V
[VREF+] – [VREF-]
20. The logic supply can be any value VL – VLR = +1.71 to +3.465 volts as long as VLR ≥ V2- and VL ≤ 3.465 V.
21. The differential voltage reference magnitude is constrained by the V1+ or V1- supply magnitude.
ABSOLUTE MAXIMUM RATINGS
(VLR = 0V)
Parameter
Symbol
Min
Typ
Max
Unit
DC Power Supplies:
[V1+] – [V1-] (Note 22)
VL + [ |V1-| ] (Note 23)
-
-
0
0
-
-
5.5
6.1
V
V
Input Current, Any Pin Except Supplies
Analog Input Voltage
(Note 24)
IIN
-
-
-
-
-
±10
(V1+) + 0.3
VL + 0.3
150
mA
V
(AIN and VREF pins)
VINA
VIND
Tstg
(V1-) – 0.3
VLR – 0.3
-65
Digital Input Voltage
V
Storage Temperature
°C
Notes: 22. V1+ = V2+; V1- = V2-
23. V1- = V2-
24. Transient currents of up to 100 mA will not cause SCR latch-up.
WARNING:
Recommended Operating Conditions indicate limits to which functional operation of the device is guaran-
teed. Absolute Maximum Ratings indicate limits beyond which permanent damage to the device may oc-
cur. The Absolute Maximum Ratings are stress ratings only and the device should not be operated at
these limits. Operation at conditions beyond the Recommended Operating Conditions may affect device
reliability; functional operation beyond Recommended Operating Conditions is not implied. Performance
specifications are guaranteed under the conditions specified for each table in the Characteristics and
Specifications section.
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CS5571
2. OVERVIEW
The CS5571 is a 16-bit analog-to-digital converter capable of 100 kSps conversion rate. The analog input
accepts a single-ended input with a magnitude of ±VREF / 2 volts. The device is capable of switching mul-
tiple input channels at a high rate with no loss in throughput. The ADC uses a low-latency digital filter ar-
chitecture. The filter is designed for fast settling and settles to full accuracy in one conversion.
The converter is a serial output device. The serial port can be configured to function as either a master or
a slave.
The CS5571 provides self-calibration circuitry to achieve low offset and gain errors.
The converter can operate from an analog supply of 5V or from ±2.5V. The digital interface supports stan-
dard logic operating from 1.8, 2.5, or 3.3 V.
The CS5571 may convert at rates up to 100 kSps when operating from a 16 MHz input clock.
3. THEORY OF OPERATION
The CS5571 converter provides high-performance measurement of DC or AC signals. The converter in-
cludes on-chip calibration circuitry to minimize offset and gain errors. The converter can be used to per-
form single conversions or continuous conversions upon command. Each conversion is independent of
previous conversions and settles to full specified accuracy, even with a full-scale input voltage step. This
is due to the converter architecture which uses a combination of a high-speed delta-sigma modulator and
a low-latency filter architecture.
Once power is established to the converter, a reset must be performed. A reset initializes the internal con-
verter logic and sets the offset register to zero and the gain register to a decimal value of 1.0. If the CAL
pin is low when RST returns high, no calibration will be performed. If CAL is high when RST transitions
from low to high, the converter’s offset & gain slope will be calibrated.
If CONV is held low then the converter will convert continuously with RDY falling every 160 MCLKs. This
is equivalent to 100 kSps if MCLK = 16.0 MHz. If CONV is tied to RDY, a conversion will occur every 162
MCLKs. If CONV is operated asynchronously to MCLK, it may take up to 164 MCLKs from CONV falling
to RDY falling.
Multiple converters can operate synchronously if they are driven by the same MCLK source and CONV
to each converter falls on the same MCLK falling edge. Alternately, CONV can be held low and all devices
are reset with RST rising on the same falling edge of MCLK.
The output coding of the conversion word is a function of the BP/UP pin.
3.1 Reset and Calibration
After the power supplies and the voltage reference are stable, the converter must be reset. The reset func-
tion initializes the internal logic in the converter, but does not initiate calibration. After reset has been per-
formed, the converter can be used uncalibrated, or calibration can be performed. Calibration minimizes
offset and gain errors inside the converter. If the device is used without calibration, conversions will in-
clude the offset and gain errors of the uncalibrated converter, but the converter will maintain its differential
and integral linearity. Calibration of offset and gain can be performed upon command.
Calibration can be initiated in either of two ways. If CAL is high when RST transitions from low to high a
calibration cycle will be performed immediately after a reset is performed. When calibration is performed,
the offset and full-scale points of the converter are calibrated. A calibration cycle takes 327,680 MCLK
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CS5571
cycles. The RDY signal falls upon completion of reset and calibration sequence. If CAL remains low when
RST transitions from low to high, no calibration will be performed. Calibrations can be initiated any time
the converter is idle by taking the CAL input high. RDY will fall at the end of the calibration cycle. The CAL
pin should be returned low when not being used.
A calibration cycle calibrates the offset and full-scale points of the converter transfer function. When the
offset portion of the calibration is performed, the AIN and ACOM pins are disconnected from the input and
shorted internally. The offset of the converter is then measured and a correction factor is stored in a reg-
ister. Then the voltage reference is internally connected to act as the input signal to the converter and a
gain calibration is performed. The gain correction results are also placed in a register. The contents of the
offset and gain registers are used to map the conversion data prior to its output from the converter.
3.2 Performing Conversions
The CS5571 converts at 100 kSps when synchronously operated (CONV = VLR) from a 16.0 MHz master
clock. Conversion is initiated by taking CONV low. A conversion lasts 160 master clock cycles, but if
CONV is asynchronous to MCLK there may be an uncertainty of 0-4 MCLK cycles after CONV falls to
when a conversion actually begins. This may extend the throughput to 164 MCLKs per conversion.
When the conversion is completed, the output word is placed into the serial port and RDY goes low. To
convert continuously, CONV should be held low. In continuous conversion mode with CONV held low, a
conversion is performed in 160 MCLK cycles. Alternately RDY can be tied to CONV and a conversion will
occur every 162 MCLK cycles.
To perform only one conversion, CONV should return high at least 20 master clock cycles before RDY
falls.
Once a conversion is completed and RDY falls, RDY will return high when all the bits of the data word are
emptied from the serial port or if the conversion data is not read and CS is held low, RDY will go high two
MCLK cycles before the end of conversion. RDY will fall at the end of the next conversion when new data
is put into the port register.
See Serial Port on page 23 for information about reading conversion data.
Conversion performance can be affected by several factors. These include the choice of clock source for
the chip, the timing of CONV, the setting of the DITHER function, and the choice of the serial port mode.
The converter can be operated from an internal oscillator. This clock source has greater jitter than an
external crystal-based clock. Jitter may not be an issue when measuring DC signals, or very-low-fre-
quency AC signals, but can become an issue for higher frequency AC signals. For maximum performance
when digitizing AC signals, a low-jitter MCLK should be used.
To achieve the highest resolution when measuring a DC signal with a single conversion the DITHER func-
tion should be off. If averaging is to be performed with multiple conversions of a DC signal, DITHER
should be on. To maximize performance, the CONV pin should be held low in the continuous conversion
state to perform multiple conversions, or CONV should occur synchronous to MCLK, falling when MCLK
falls.
When performing conversions on an AC signal, CONV should be held low in the continuous conversion
state to perform multiple conversions, or CONV should occur synchronous to MCLK, falling when MCLK
falls.
If the converter is operated at maximum throughput, the SSC serial port mode is less likely to cause in-
terference to measurements as the SCLK output is synchronized to the MCLK. Alternately, any interfer-
14
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CS5571
ence due to serial port clocking can also be minimized if data is read in the SEC serial port mode when a
conversion is not is progress.
3.3 Clock
The CS5571 can be operated from its internal oscillator or from an external master clock. The state of
MCLK determines which clock source will be used. If MCLK is tied low, the internal oscillator will start and
be used as the clock source for the converter. If an external CMOS-compatible clock is input into MCLK,
the converter will power down the internal oscillator and use the external clock. If the MCLK pin is held
high, the internal oscillator will be held in the stopped state. The MCLK input can be held high to delete
clock cycles to aid in operating multiple converters in different phase relationships.
The internal oscillator can be used if the signals to be measured are essentially DC. The internal oscillator
exhibits jitter at about 500 picoseconds rms. If the CS5571 is used to digitize AC signals, an external
low-jitter clock source should be used.
If the internal oscillator is used as the clock for the CS5571, the maximum conversion rate will be dictated
by the oscillator frequency.
3.4 Voltage Reference
The voltage reference for the CS5571 can range from 2.4 volt to 4.2 volts. A 4.096 volt reference is re-
quired to achieve the specified signal-to-noise performance. Figure 5 and Figure 6 illustrate the connec-
tion of the voltage reference with either a single +5 V analog supply or with ±2.5 V.
For optimum performance, the voltage reference device should be one that provides a capacitor connec-
tion to provide a means of noise filtering, or the output should include some type of bandwidth-limiting fil-
ter.
Some 4.096 volt reference devices need only 5 volts total supply for operation and can be connected as
shown in Figure 5 or Figure 6. The reference should have a local bypass capacitor and an appropriate
output capacitor.
Some older 4.096 voltage reference designs require more headroom and must operate from an input volt-
age of 5.5 to 6.5 volts. If this type of voltage reference is used ensure that when power is applied to the
system, the voltage reference rise time is slower than the rise time of the V1+ and V1- power supply volt-
age to the converter. An example circuit to slow the output startup time of the reference is illustrated in
Figure 4.
5.5 to 15 V
2k
10µF
VIN
VOUT
GND
4.096 V
Refer to V1- and VREF1 pins.
Figure 4. Voltage Reference Circuit
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CS5571
3.5 Analog Input
The analog input of the converter is single-ended with an full-scale input of ±2.048 volts. This is illustrated
in Figure 5 and Figure 6. These diagrams also illustrate a differential buffer amplifier configuration for driv-
ing the CS5571.
The capacitors at the outputs of the amplifiers provide a charge reservoir for the dynamic current from the
A/D inputs while the resistors isolate the dynamic current from the amplifier. The amplifiers can be pow-
ered from higher supplies than those used by the A/D but precautions should be taken to ensure that the
op-amp output voltage remains within the power supply limits of the A/D, especially under start-up condi-
tions.
3.6 Output Coding Format
The reference voltage directly defines the input voltage range in both the unipolar and bipolar configura-
tions. In the unipolar configuration (BP/UP low), the first code transition occurs 0.5 LSB above zero, and
the final code transition occurs 1.5 LSBs below VREF. In the bipolar configuration (BP/UP high), the first
code transition occurs 0.5 LSB above -VREF and the last transition occurs 1.5 LSBs below +VREF. See
Table 1 for the output coding of the converter.
Table 1. Output Coding, Two’s Complement
Two’s
Bipolar Input Voltage
Complement
>(VREF-1.5 LSB)
VREF-1.5 LSB
7F FF
7F FF
7F FE
00 00
-0.5 LSB
FF FF
80 01
-VREF+0.5 LSB
80 00
80 00
<(-VREF+0.5 LSB)
NOTE: VREF = [(VREF+) - (VREF-)] / 2
Table 2. Output Coding, Offset Binary
Offset
Unipolar Input Voltage
Binary
>(VREF-1.5 LSB)
FF FF
FF FF
VREF-1.5 LSB
FF FE
80 00
(VREF/2)-0.5 LSB
7F FF
00 01
+0.5 LSB
00 00
00 00
<(+0.5 LSB)
NOTE: VREF = [(VREF+) - (VREF-)] / 2
16
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CS5571
3.7 Typical Connection Diagrams
The following figure depicts the CS5571 powered from bipolar analog supplies, +2.5 V and - 2.5 V.
+2.048 V
0 V
CS5571
-2.048 V
49.9
AIN
150pF
2k
2200pF
C0G
SMODE
CS
4SCLK
4SDO
RDY
ACOM
(V+) Buffers On
(V-) Buffers Off
BUFEN
VREF+
CONV
CAL
+2.5 V
BP/UP
DITHER
+4.096
Voltage
Reference
(NOTE 1)
RST
10 µF
0.1 µF
MCLK
TST
VREF-
-2.5 V
+3.3 V to +1.8 V
+2.5 V
V1+
V2+
V2-
VL
10
0.1 µF
0.1 µF
0.1 µF
10
0.1 µF
X7R
DCR
V1-
VLR
-2.5 V
NOTES
1. See Section 3.4 Voltage Reference for information on required
voltage reference performance criteria.
2.Locate capacitors so as to minimize loop length.
3. The ±2.5 V supplies should also be bypassed to ground at the converter.
4. VLR and the power supply ground for the ±2.5 V should be
connected to the same ground plane under the chip.
5. SCLK and SDO may require pull-down resistors in some applications.
Figure 5. CS5571 Configured Using ±2.5V Analog Supplies
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CS5571
The following figure depicts the CS5571 part powered from a single 5V analog supply and configured for
unipolar measurement.
0 V to +2.048 V
CS5571
49.9
AIN
SMODE
CS
2200pF
C0G
150pF
2k
3SCLK
3SDO
RDY
ACOM
(V+) Buffers On
(V-) Buffers Off
BUFEN
CONV
CAL
+5 V
BP/UP
DITHER
RST
VREF+
VREF-
+4.096
Voltage
Reference
(NOTE 1)
10 µF
0.1 µF
MCLK
TST
+3.3 V to 1.8 V
+5 V
V1+
V2+
V2-
VL
10
0.1 µF
0.1 µF
0.1 µF
0.1 µF
X7R
DCR
V1-
VLR
NOTES
1. See Section 3.4 Voltage Reference for information on
required voltage reference performance criteria.
2. Locate capacitors so as to minimize loop length.
3. V1-, V2-, and VLR should be connected to the same
ground plane under the chip.
4. SCLK and SDO may require pull-down resistors in
some applications.
Figure 6. CS5571 Configured for Unipolar Measurement Using a Single 5V Analog Supply
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CS5571
The following figure depicts the CS5571 part powered from a single 5V analog supply and configured for
bipolar measurement, referenced to a common mode voltage of 2.5 V.
+4.548 V
+2.5 V
-0.452 V
CS5571
49.9
AIN
2200pF
C0G
150pF
2k
SMODE
CS
Common Mode Voltage
(2.5 V Typ.)
3SCLK
49.9
ACOM
2200pF
C0G
150pF
2k
3SDO
RDY
(V+) Buffers On
(V-) Buffers Off
CONV
CAL
BUFEN
VREF+
+5 V
BP/UP
DITHER
RST
+4.096
Voltage
Reference
(NOTE 1)
10 µF
0.1 µF
MCLK
TST
VREF-
+3.3 V to 1.8 V
+5 V
V1+
V2+
V2-
VL
10
0.1 µF
0.1 µF
0.1 µF
0.1 µF
X7R
DCR
V1-
VLR
NOTES
1. See Section 3.4 Voltage Reference for information on
required voltage reference performance criteria.
2. Locate capacitors so as to minimize loop length.
3. V1-, V2-, and VLR should be connected to the same
ground plane under the chip.
4. SCLK and SDO may require pull-down resistors in
some applications.
Figure 7. CS5571 Configured for Bipolar Measurement Using a Single 5V Analog Supply
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CS5571
3.8 AIN & VREF Sampling Structures
The CS5571 uses on-chip buffers on the AIN, ACOM, and the VREF+ inputs. Buffers provide much higher
input impedance and therefore reduce the amount of drive current required from an external source. This
helps minimize errors.
The Buffer Enable (BUFEN) pin determines if the on-chip buffers are used or not. If the BUFEN pin is
connected to the V1+ supply the buffers will be enabled. If the BUFEN pin is connected to the V1- pin
the buffers are off. The converter will consume about 30 mW less power when the buffers are off, but the
input impedances of AIN, ACOM and VREF+ will be significantly less than with the buffers enabled.
3.9 Converter Performance
The CS5571 achieves excellent differential nonlinearity (DNL) as shown in Figures 8 and 9. Figure 8 il-
lustrates the code widths on the typical scale of +/- 1 LSB and on a zoomed scale of ±0.1 LSB. The DNL
error histogram in Figure 9 indicates that more than half the codes are accurate to better than ±0.01 LSB.
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
-1.00
0.10
0.08
0.06
0.04
0.02
0.00
-0.02
-0.04
-0.06
-0.08
-0.10
1
65535
1
65535
Codes
Codes
(Zoom View)
Figure 8. CS5571 DNL Plot
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
DNL Error in LSBs
Figure 9. CS5571 DNL Histogram
20
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CS5571
This excellent DNL performance impacts small-signal performance. For small signals, an error in the size
of a code represents a much greater percentage of the signal than with a full-scale input signal. Figure
10 illustrates the small-signal performance of the CS5571. The signal is at -80 dB from full scale. There-
fore, the input is at 1/10,000th of full scale, having a peak-to-peak magnitude of only a few codes. Excel-
lent DNL and proper dither allows the CS5571 to achieve high spectral purity with very small signals.
0
Input Signal = 1 kHz @ -80 dB
64k Samples @ 100 kSps
DITHER ON
-20
-40
-60
-80
-100
-120
-140
-160
-180
0
5k
10k
15k
20k
25k
30k
35k
40k
45k
50k
Frequency (Hz)
Figure 10. CS5571 Small Signal Performance (Dither On)
0
-20
Input Signal = 1 kHz @ -80 dB
64k Samples @ 100 kSps
DITHER OFF
-40
-60
-80
-100
-120
-140
-160
-180
0
5k
10k
15k
20k
25k
30k
35k
40k
45k
50k
Frequency (Hz)
Figure 11. CS5571 Small Signal Performance (Dither Off)
Figure 11 illustrates the performance of the CS5571 under the same signal conditions as figure 10 but
with DITHER set to OFF. For small signals, good DNL alone is not adequate as the quantization itself can
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CS5571
introduce distortion components unless there is an appropriate amount of dither present. DITHER in the
CS5571 can be set to ON for AC signal measurement or for averaging DC signals. DITHER can be set to
OFF for improved resolution when performing a single conversion on a DC signal.
3.10 Digital Filter Characteristics
The digital filter is designed for fast settling, therefore it exhibits very little in-band attenuation. The filter
attenuation is 1.040 dB at 50 kHz when sampling at 100 kSps.
0.00
-0.0414 dB
fs = 100 kSps
-0.1660 dB
-0.25
-0.3740 dB
-0.50
-0.75
-0.6660 dB
-1.00
-1.040 dB
-1.25
-1.50
0
10k
20k
30k
40k
50k
Frequency (Hz)
Figure 12. CS5571 Spectral Response (DC to fs/2)
0.00
-0.001650 dB
fs = 100 kSps
-0.00700 dB
-0.01
-0.01490 dB
-0.02
-0.02643 dB
-0.03
-0.04
-0.04140 dB
-0.05
0
2k
4k
6k
8k
10k
Frequency (Hz)
Figure 13. CS5571 Spectral Response (DC to 10 kHz)
0
fs = 100 kSps
-20
-40
-60
-80
-100
-120
0
100k
200k
300k
400k
Frequency (Hz)
Figure 14. CS5571 Spectral Response (DC to 4fs)
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CS5571
3.11 Serial Port
The serial port on the CS5571 can operate in two different modes: synchronous self clock (SSC) mode &
synchronous external clock (SEC) mode. The serial port must be placed into the SEC mode if the offset
and gain registers of the converter are to be read or written. The converter must be idle when reading or
writing to the on-chip registers.
3.11.1 SSC Mode
If the SMODE pin is high (SMODE = VL), the serial port operates in the SSC (Synchronous Self Clock)
mode. In the SSC mode the port shifts out conversion data words with SCLK as an output. SCLK is gen-
erated inside the converter from MCLK. Data is output from the SDO (Serial Data Output) pin. If CS is
high, the SDO and SCLK pins will stay in a high-impedance state. If CS is low when RDY falls, the con-
version data word will be output from SDO MSB first. Data is output on the rising edge of SCLK and should
be latched into the external logic on the subsequent rising edge of SCLK. When all bits of the conversion
word are output from the port the RDY signal will return to high.
3.11.2 SEC Mode
If the SMODE pin is low (SMODE = VLR), the serial port operates in the SEC (Synchronous External
Clock mode). In this mode, the user usually monitors RDY. When RDY falls at the end of a conversion,
the conversion data word is placed into the output data register in the serial port. CS is then activated low
to enable data output. Note that CS can be held low continuously if it is not necessary to have the SDO
output operate in the high impedance state. When CS is taken low (after RDY falls) the conversion data
word is then shifted out of the SDO pin by driving the SCLK pin from system logic external to the converter.
Data bits are advanced on rising edges of SCLK and latched by the subsequent rising edge of SCLK.
If CS is held low continuously, the RDY signal will fall at the end of a conversion and the conversion data
will be placed into the serial port. If the user starts a read, the user will maintain control over the serial port
until the port is empty. However, if SCLK is not toggled, the converter will overwrite the conversion data
at the completion of the next conversion. If CS is held low and no read is performed, RDY will rise just
prior to the end of the next conversion and then fall to signal that new data has been written into the serial
port.
3.12 Power Supplies & Grounding
The CS5571 can be configured to operate with its analog supply operating from 5V, or with its analog sup-
plies operating from ±2.5V. The digital interface supports digital logic operating from either 1.8V, 2.5V, or
3.3V.
Figure 5 on page 17 illustrates the device configured to operate from ±2.5V analog. Figure 6 on page 18
illustrates the device configured to operate from 5V analog.
To maximize converter performance, the analog ground and the logic ground for the converter should be
connected at the converter. In the dual analog supply configuration, the analog ground for the ±2.5V sup-
plies should be connected to the VLR pin at the converter with the converter placed entirely over the an-
alog ground plane.
In the single analog supply configuration (+5V), the ground for the +5V supply should be directly tied to
the VLR pin of the converter with the converter placed entirely over the analog ground plane. Refer to
Figure 6 on page 18.
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CS5571
3.13 Using the CS5571 in Multiplexing Applications
The CS5571 is a delta-sigma A/D converter. Delta-sigma converters use oversampling as means to
achieve high signal to noise. This means that once a conversion is started the converter takes many sam-
ples to compute the resulting output word. The analog input for the signal to be converted must remain
active during the entire conversion until RDY falls.
The CS5571 can be used in multiplexing applications, but the system timing for changing the multiplexer
channel and for starting a new conversion will depend upon the multiplexer system architecture.
The simplest system is illustrated in Figure 15. Any time the multiplexer is changed, the analog signal
presented to the converter must fully settle. After the signal has settled, the CONV signal is issued to the
converter to start a conversion. Being a delta-sigma converter, the signal must remain present at the input
of the converter until the conversion is completed. Once the conversion is completed, RDY falls. At this
time the multiplexer can be changed to the next channel and the data can be read from the serial port.
The CONV signal should be delayed until after the data is read and until the new analog signal has settled.
In this configuration, the throughput of the converter will be dictated by the settling time of the analog input
circuit and the conversion time of the converter. The conversion data can be read from the serial port after
the multiplexer is changed to the new channel while the analog input signal is settling.
CS5571
CH1
90
AIN
CH2
CH3
CH4
150pF
2k
1000pF
C0G
ACOM
Amplifier
Settling Time
Amplifier
Settling Time
Conversion Time
CONV
RDY
CH1
CH2
Advance
Mux
Throughput
Figure 15. Simple Multiplexing Scheme
A more complex multiplexing scheme can be used to increase the throughput of the converter is illustrated
in Figure 16. In this circuit, two banks of multiplexers are used.
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At the same time the converter is performing a conversion on a channel from one bank of multiplexers,
the second multiplexer bank is used to select the channel for the next conversion. This configuration al-
lows the buffer amplifier for the second multiplexer bank to fully settle while a conversion is being per-
formed on the channel from the first multiplexer bank. The multiplexer on the output of the buffer amplifier
and the CONV signal can be changed at the same time in this configuration. This multiplexing architec-
ture allows for maximum multiplexing throughput from the A/D converter.The following figure depicts the
recommended analog input amplifier circuit.
SW2
CS5571
CH1
CH3
A1
A2
90
SW1
150pF
1000pF
C0G
AIN
2k
SW3
CH2
CH4
90
150pF
1000pF
C0G
ACOM
2k
CONV
SW1
SW2
SW3
Select A1
Select A2
Select A1
Select A2
Select A1
Select CH1
Select CH2
Select CH3
Select CH1
Select CH4
Select CH2
Convert on CH1
Convert on CH2
Convert on CH3
Convert on CH4
Convert on CH1
Figure 16. More Complex Multiplexing Scheme
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3.14 Synchronizing Multiple Converters
Many measurement systems have multiple converters that need to operate synchronously. The convert-
ers should all be driven from the same master clock. In this configuration, the converters will convert syn-
chronously if the same CONV signal is used to drive all the converters, and CONV falls on a falling edge
of MCLK. If CONV is held low continuously, reset (RST) can be used to synchronize multiple converters
if RST is released on a falling edge of MCLK.
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CS5571
4. PIN DESCRIPTIONS
Chip Select
CS
TST
SMODE
AIN
1
2
3
4
24
23
22
21
20
19
18
17
16
15
14
13
RDY
SCLK
SDO
VL
Ready
Factory Test
Serial Mode Select
Analog Input
Serial Clock Input/Output
Serial Data Output
Logic Interface Power
Logic Interface Return
Master Clock
Negative Voltage 2
Positive Voltage 2
Digital Core Regulator
Convert
Analog Common
Negative Power 1
Positive Power 1
ACOM
V1-
5
6
7
8
VLR
MCLK
V2-
V1+
Buffer Enable
BUFEN
VREF+
VREF-
BP/UP
DITHER
V2+
Voltage Reference Input
Voltage Reference Input
Bipolar/Unipolar Select
Dither Select
9
DCR
CONV
CAL
RST
10
11
12
Calibrate
Reset
CS – Chip Select, Pin 1
The Chip Select pin allows an external device to access the serial port. When held high, the
SDO output will be held in a high-impedance output state.
TST – Factory Test, Pin 2
For factory use only. Tie to VLR.
SMODE – Serial Mode Select, Pin 3
The serial interface mode pin (SMODE) dictates whether the serial port behaves as a master or
slave interface.If SMODE is tied high (to VL), the port will operate in the Synchronous
Self-Clocking (SSC) mode. In SSC mode the port acts as a master in which the converter out-
puts both the SDO and SCLK signals. If SMODE is tied low (to VLR) the port will operate in the
Synchronous External Clocking (SEC) mode. In SEC mode, the port acts as a slave in which
the external logic or microcontroller generates the SCLK used to output the conversion data
word from the SDO pin.
AIN, ACOM – Differential Analog Input, Pin 4, 5
AIN and ACOM are the single-ended input and the analog return for the input signal, respec-
tively.
V1- – Negative Power 1, Pin 6
The V1- and V2- pins provide a negative supply voltage to the core circuitry of the chip. These
two pins should be decoupled as shown in the application block diagrams. V1- and V2- should
be supplied from the same source voltage. For single supply operation these two voltages are
nominally 0 V (Ground). For dual supply operation they are nominally -2.5 V.
V1+ – Positive Power 1, Pin 7
The V1+ and V2+ pins provide a positive supply voltage to the core circuitry of the chip. These
two pins should be decoupled as shown in the application block diagrams. V1+ and V2+ should
be supplied from the same source voltage. For single supply operation these two voltages are
nominally +5 V. For dual supply operation they are nominally +2.5 V.
BUFEN – Buffer Enable, Pin 8
Buffers on input pins AIN and ACOM are enabled if BUFEN is connected to V1+ and disabled if
connected to V1-.
VREF+, VREF- – Voltage Reference Input, Pin 9, 10
A differential voltage reference input on these pins functions as the voltage reference for the
converter. The voltage between these pins can range between 2.4 volts and 4.2 volts, with
4.096 volts being the nominal reference voltage value.
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BP/UP – Bipolar/Unipolar Select, Pin 11
The BP/UP pin determines the span and the output coding of the converter. When set high to
select BP (bipolar), the input span of the converter is -2.048 volts to +2.048 volts (assuming the
voltage reference is 4.096 volts) and outputs data is coded in two's complement format. When
set low to select UP (unipolar), the input span is 0 to +2.048 and the output data is coded in
binary format.
DITHER – Dither Select, Pin 12
When DITHER is high (DITHER = VL), output conversion words will be dithered. When DITHER
is low (DITHER = VLR), output words will be dominated by quantization.
RST – Reset, Pin 13
Reset is necessary after power is initially applied to the converter. When the RST input is taken
low, the logic in the converter will be reset. When RST is released to go high, certain portions of
the analog circuitry are started. RDY falls when reset is complete.
CAL – Calibrate, Pin 14
After power is applied, a reset should be performed prior to calibration. After an initial reset, cal-
ibration can be performed at any time. Calibration can be initiated in either of two ways. If CAL
is high when coming out of reset, (RST going high), a calibration will be performed. If RST is
taken high with CAL low, a calibration is not performed, but calibration can be initiated by taking
CAL high at any time the converter is idle. RDY will also fall when calibration is completed.
CONV – Convert, Pin 15
The CONV pin initiates a conversion cycle if taken low, unless a calibration cycle or a previous
conversion is in progress. When the conversion cycle is completed, the conversion word is out-
put to the serial port register and the RDY signal goes low. If CONV is held low and remains low
when RDY falls another conversion cycle will be started.
DCR – Digital Core Regulator, Pin 16
DCR is the output of the on-chip regulator for the digital logic core. DCR should be bypassed
with a capacitor to V2-. The DCR pin is not designed to power any external load.
V2+ – Positive Power 2, Pin 17
The V1+ and V2+ pins provide a positive supply voltage to the circuitry of the chip. These two
pins should be decoupled as shown in the application block diagrams. V1+ and V2+ should be
supplied from the same source voltage. For single supply operation these two voltages are
nominally +5 V. For dual supply operation they are nominally +2.5 V.
V2- – Negative Power 2, Pin 18
The V1- and V2- pins provide a negative supply voltage to the circuitry of the chip. These two
pins should be decoupled as shown in the application block diagrams. V1- and V2- should be
supplied from the same source voltage. For single supply operation these two voltages are
nominally 0 V (Ground). For dual supply operation they are nominally -2.5 V.
MCLK – Master Clock, Pin 19
The master clock pin (MCLK) is a multi-function pin. If tied low (MCLK = VLR) the on-chip oscil-
lator will be enabled. If tied high (MCLK = VL), all clocks to the internal circuitry of the converter
will stop. When MCLK is held high the internal oscillator will also be stopped. MCLK can also
function as the input for an external CMOS-compatible clock that conforms to supply voltages
on the VL and VLR pins.
VLR, VL – Logic Interface Power/Return, Pin 20, 21
VL and VLR are the supply voltages for the digital logic interface. VL and VLR can be config-
ured with a wide range of common mode voltage. The following interface pins function from the
VL/VLR supply: SMODE, CS, SCLK, TST, SDO, RDY, DITHER, CONV, RST, CONV, CAL,
BP/UP, and MCLK.
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SDO – Serial Data Output, Pin 22
SDO is the output pin for the serial output port. Data from this pin will be output at a rate deter-
mined by SCLK and in a format determined by the BP/UP pin. Data is output MSB first and
advances to the next data bit on the rising edges of SCLK. SDO will be in a high impedance
state when CS is high.
SCLK – Serial Clock Input/Output, Pin 23
The SMODE pin determines whether the SCLK signal is an input or an output signal. SCLK
determines the rate at which data is clocked out of the SDO pin. If the converter is in SSC
mode, the SCLK frequency will be determined by the master clock frequency of the converter
(either MCLK or the internal oscillator). In SEC mode, the user determines the SCLK frequency.
If SCLK is an output (SMODE = VL), it will be in a high-impedance state when CS is high.
RDY – Ready, Pin 24
The RDY signal rises when a calibration is initiated. When the calibration is near completion the
state of CONV is examined. If CONV is high, the RDY signal will fall upon the completion of cal-
ibration. If CONV is low the converter will immediately start a conversion and RDY will remain
high until the conversion is completed. At the end of any conversion RDY falls to indicate that a
conversion word has been placed into the serial port. RDY will return high after all data bits are
shifted out of the serial port or two master clock cycles before new data becomes available if the
CS pin is inactive (high); or two master clock cycles before new data becomes available if the
user holds CS low but has not started reading the data from the converter when in SEC mode.
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CS5571
5. PACKAGE DIMENSIONS
24L SSOP PACKAGE DRAWING
N
D
E11
A2
A
E
∝
A1
b2
e
L
END VIEW
SEATING
PLANE
SIDE VIEW
1
2 3
TOP VIEW
INCHES
NOM
--
0.006
0.068
--
0.323
0.307
0.209
0.026
0.03
4°
MILLIMETERS
NOTE
DIM
A
A1
A2
b
D
E
E1
e
L
MIN
--
MAX
0.084
0.010
0.074
0.015
0.335
0.323
0.220
0.030
0.041
8°
MIN
--
NOM
--
0.13
1.73
--
8.20
7.80
5.30
0.65
0.75
4°
MAX
2.13
0.25
1.88
0.38
8.50
8.20
5.60
0.75
1.03
8°
0.002
0.064
0.009
0.311
0.291
0.197
0.022
0.025
0°
0.05
1.62
0.22
7.90
7.40
5.00
0.55
0.63
0°
2,3
1
1
∝
JEDEC #: MO-150
Controlling Dimension is Millimeters.
Notes: 1.“D” and “E1” are reference datums and do not included mold flash or protrusions, but do include mold mismatch and are measured
at the parting line, mold flash or protrusions shall not exceed 0.20 mm per side.
2.Dimension “b” does not include dambar protrusion/intrusion. Allowable dambar protrusion shall be 0.13 mm total in excess of “b”
dimension at maximum material condition. Dambar intrusion shall not reduce dimension “b” by more than 0.07 mm at least
material condition.
3.These dimensions apply to the flat section of the lead between 0.10 and 0.25 mm from lead tips.
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6. ORDERING INFORMATION
Model
CS5571-ISZ
Linearity
Temperature
-40 to +85 °C
Conversion Time
Throughput
Package
TBD
10 µs
100 kSps
24-pin SSOP
7. ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION
Model Number
CS5571-ISZ
Peak Reflow Temp
MSL Rating*
Max Floor Life
7 Days
260 °C
3
* MSL (Moisture Sensitivity Level) as specified by IPC/JEDEC J-STD-020.
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8. REVISION HISTORY
Revision
A1
Date
Changes
MAR 2007
MAR 2007
APR 2007
JUN 2007
JUN 2007
Advance release.
Updated characterization data.
A2
A3
Added typ. connection diagrams for unipolar and bipolar measurement.
Updated serial interface timing parameters.
Corrected Figure 7.
A4
A5
Contacting Cirrus Logic Support
For all product questions and inquiries contact a Cirrus Logic Sales Representative.
To find the one nearest to you go to www.cirrus.com
IMPORTANT NOTICE
"Advance" product information describes products that are in development and subject to development changes.
Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject
to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant
information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus
for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third
parties. This document is the property of Cirrus and by furnishing this information, Cirrus grants no license, express or implied under any patents, mask work rights,
copyrights, trademarks, trade secrets or other intellectual property rights. Cirrus owns the copyrights associated with the information contained herein and gives con-
sent for copies to be made of the information only for use within your organization with respect to Cirrus integrated circuits or other products of Cirrus. This consent
does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROP-
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IN AIRCRAFT SYSTEMS, MILITARY APPLICATIONS, PRODUCTS SURGICALLY IMPLANTED INTO THE BODY, AUTOMOTIVE SAFETY OR SECURITY DE-
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Cirrus Logic, Cirrus, and the Cirrus Logic logo designs are trademarks of Cirrus Logic, Inc. All other brand and product names in this document may be trademarks
or service marks of their respective owners.
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