DAC8532 [BB]
Dual Channel, Low Power, 16-Bit, Serial Input DIGITAL-TO-ANALOG CONVERTER; 双通道，低功耗， 16位，串行输入数位类比转换器
| 型号： | DAC8532 |
| 厂家： | 
BURR-BROWN CORPORATION |
| 描述： | Dual Channel, Low Power, 16-Bit, Serial Input DIGITAL-TO-ANALOG CONVERTER |
| 文件： | 总19页 (文件大小：399K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DAC8532
SBAS246A – DECEMBER 2001 – MAY 2003
Dual Channel, Low Power, 16-Bit, Serial Input
DIGITAL-TO-ANALOG CONVERTER
DESCRIPTION
FEATURES
The DAC8532 is a dual channel, 16-bit Digital-to-Analog
Converter (DAC) offering low power operation and a flexible
serial host interface. Each on-chip precision output amplifier
allows rail-to-rail output swing to be achieved over the supply
range of 2.7V to 5.5V. The device supports a standard 3-wire
serial interface capable of operating with input data clock
frequencies up to 30MHz for VDD = 5V.
ꢀꢀmicroPOWER OPERATION: 500
POWER-ON RESET TO ZERO-SCALE
ꢀ POWER SUPPLY: +2.7V to +5.5V
µA at 5V
ꢀ
ꢀ 16-BIT MONOTONIC OVER TEMPERATURE
ꢀ SETTLING TIME: 10µs to ±0.003% FSR
ꢀ ULTRA-LOW AC CROSSTALK: –100dB typ
The DAC8532 requires an external reference voltage to set
the output range of each DAC channel. Also incorporated
into the device is a power-on reset circuit which ensures that
the DAC outputs power up at zero-scale and remain there
until a valid write takes place. The DAC8532 provides a
flexible power-down feature, accessed over the serial inter-
face, that reduces the current consumption of the device to
200nA at 5V.
ꢀ LOW-POWER SERIAL INTERFACE WITH
SCHMITT-TRIGGERED INPUTS
ꢀ ON-CHIP OUTPUT BUFFER AMPLIFIER WITH
RAIL-TO-RAIL OPERATION
ꢀ DOUBLE BUFFERED INPUT ARCHITECTURE
ꢀ SIMULTANEOUS OR SEQUENTIAL OUTPUT
UPDATE AND POWERDOWN
ꢀ TINY MSOP-8 PACKAGE
The low-power consumption of this device in normal opera-
tion makes it ideally suited to portable battery-operated
equipment and other low-power applications. The power
consumption is 2.5mW at 5V, reducing to 1µW in power-
down mode.
APPLICATIONS
ꢀ PORTABLE INSTRUMENTATION
ꢀ CLOSED-LOOP SERVO-CONTROL
ꢀ PROCESS CONTROL
The DAC8532 is available in a MSOP-8 package with a
specified operating temperature range of –40°C to +105°C.
ꢀ DATA ACQUISITION SYSTEMS
ꢀ PROGRAMMABLE ATTENUATION
ꢀ PC PERIPHERALS
VDD
VREF
Data
Buffer A
DAC
Register A
VOUT
A
B
DAC A
DAC B
Data
Buffer B
DAC
Register B
VOUT
16
24-Bit
SYNC
SCLK
DIN
Serial-to-
Parallel
Shift
Channel
Select
Load
Control
Power-Down
Control Logic
8
2
Control Logic
Resistor
Network
Register
GND
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright © 2001-2003, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
www.ti.com
ABSOLUTE MAXIMUM RATINGS(1)
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Texas Instru-
ments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
VDD to GND ........................................................................... –0.3V to +6V
Digital Input Voltage to GND ................................. –0.3V to +VDD + 0.3V
VOUTA or VOUTB to GND .......................................... –0.3V to +VDD + 0.3V
Operating Temperature Range ...................................... –40°C to +105°C
Storage Temperature Range .........................................–65°C to +150°C
Junction Temperature Range (TJ max) ........................................ +150°C
Power Dissipation ........................................................ (TJ max — TA)/θJA
θJA Thermal Impedance ......................................................... 206°C/W
θJC Thermal Impedance .......................................................... 44°C/W
Lead Temperature, Soldering:
ESD damage can range from subtle performance degradation
tocompletedevicefailure. Precisionintegratedcircuitsmaybe
more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
Vapor Phase (60s) ............................................................... +215°C
Infrared (15s) ........................................................................ +220°C
NOTE: (1) Stresses above those listed under “Absolute Maximum Ratings”
may cause permanent damage to the device. Exposure to absolute maximum
conditions for extended periods may affect device reliability.
PACKAGE/ORDERING INFORMATION
SPECIFICATION
PACKAGE
DESIGNATOR(1)
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER
TRANSPORT
MEDIA, QUANTITY
PRODUCT
PACKAGE-LEAD
DAC8532
MSOP-8
DGK
"
–40°C to +105°C
D32E
"
DAC8532IDGK
DAC8532IDGKR
Tube, 80
Tape and Reel,
2500
"
"
NOTE: (1) For the most current specifications and package information, refer to our web site at www.ti.com.
ELECTRICAL CHARACTERISTICS
VDD = +2.7V to +5.5V. –40°C to +105°C, unless otherwise specified.
DAC8532
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE(1)
Resolution
Relative Accuracy
Differential Nonlinearity
Zero-Scale Error
16
Bits
% of FSR
LSB
±0.0987
±1
+25
16-Bit Monotonic
+5
mV
Full-Scale Error
Gain Error
Zero-Scale Error Drift
Gain Temperature Coefficient
Channel-to-Channel Matching
PSRR
–0.15
–1.0
±1.0
% of FSR
% of FSR
µV/°C
ppm of FSR/°C
mV
±20
±5
15
RL = 2kΩ, CL = 200pF
0.75
mV/V
OUTPUT CHARACTERISTICS(2)
Output Voltage Range
Output Voltage Settling Time
0
VREF
10
V
To ±0.003% FSR
0200H to FD00H
8
µs
RL = 2kΩ; 0pF < CL < 200pF
RL = 2kΩ; CL = 500pF
12
1
470
1000
20
0.5
0.25
–100
1
µs
V/µs
pF
Slew Rate
Capacitive Load Stability
R
L = ∞
RL = 2kΩ
pF
Code Change Glitch Impulse
Digital Feedthrough
DC Crosstalk
1LSB Change Around Major Carry
nV-s
nV-s
LSB
dB
AC Crosstalk
–96
DC Output Impedance
Short-Circuit Current
Ω
VDD = +5V
VDD = +3V
50
20
mA
mA
Power-Up Time
Coming Out of Power-Down Mode
VDD = +5V
2.5
5
µs
µs
Coming Out of Power-Down Mode
VDD = +3V
AC PERFORMANCE
BW = 20kHz, VDD = 5V
FOUT = 1kHz, 1st 19 Harmonics Removed
SNR
THD
SFDR
SINAD
94
67
69
65
dB
dB
dB
dB
DAC8532
SBAS246A
2
www.ti.com
ELECTRICAL CHARACTERISTICS (Cont.)
VDD = +2.7V to +5.5V. –40°C to +105°C, unless otherwise specified.
DAC8532
TYP
PARAMETER
CONDITIONS
MIN
MAX
UNITS
REFERENCE INPUT
Reference Current
V
V
REF = VDD = +5V
REF = VDD = +3V
67
40
90
54
VDD
µA
µA
V
Reference Input Range
0
Reference Input Impedance
75
kΩ
LOGIC INPUTS(2)
Input Current
±1
0.8
0.6
µA
V
V
V
V
V
V
V
V
INL, Input LOW Voltage
INL, Input LOW Voltage
INH, Input HIGH Voltage
INH, Input HIGH Voltage
VDD = +5V
VDD = +3V
VDD = +5V
VDD = +3V
2.4
2.1
Pin Capacitance
3
pF
POWER REQUIREMENTS
VDD
2.7
5.5
V
I
DD (normal mode)
VDD = +3.6V to +5.5V
DD = +2.7V to +3.6V
DD (all power-down modes)
DAC Active and Excluding Load Current
VIH = VDD and VIL = GND
VIH = VDD and VIL = GND
500
450
800
750
µA
µA
V
I
V
V
DD = +3.6V to +5.5V
DD = +2.7V to +3.6V
VIH = VDD and VIL = GND
VIH = VDD and VIL = GND
0.2
0.05
1
1
µA
µA
POWER EFFICIENCY
OUT/IDD
I
ILOAD = 2mA, VDD = +5V
89
%
TEMPERATURE RANGE
Specified Performance
–40
+105
°C
NOTES: (1) Linearity calculated using a reduced code range of 485 to 64714; output unloaded. (2) Ensured by design and characterization, not production tested.
PIN CONFIGURATION
PIN DESCRIPTIONS
PIN
NAME
DESCRIPTION
Top View
MSOP-8
1
2
3
4
5
VDD
Power supply input, +2.7V to +5.5V.
Reference voltage input.
VREF
VOUTB
Analog output voltage from DAC B.
Analog output voltage from DAC A.
V
OUTA
SYNC
Level triggered SYNC input (active LOW). This is the
frame synchronization signal for the input data.
When SYNC goes LOW, it enables the input shift
register and data is transferred on the falling edge of
SCLK. The action specified by the 8-bit control byte
and 16-bit data word is executed following the 24th
falling SCLK clock edge (unless SYNC is taken
HIGH before this edge in which case the rising edge
of SYNC acts as an interrupt and the write sequence
is ignored by the DAC8532).
1
2
3
4
VDD
8
7
6
5
GND
DIN
VREF
DAC8532
VOUT
B
SCLK
SYNC
V
OUTA
6
7
SCLK
DIN
Serial Clock Input. Data can be transferred at rates
up to 30 MHz at 5V.
Serial Data Input. Data is clocked into the 24-bit
input shift register on each falling edge of the serial
clock input.
8
GND
Ground reference point for all circuitry on the part.
DAC8532
SBAS246A
3
www.ti.com
TIMING CHARACTERISTICS(1, 2)
VDD = +2.7V to +5.5V; all specifications –40°C to +105°C unless otherwise noted.
DAC8532
TYP
PARAMETER
DESCRIPTION
CONDITIONS
MIN
MAX
UNITS
(3)
t1
SCLK Cycle Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
50
33
ns
ns
t2
t3
t4
SCLK HIGH Time
SCLK LOW Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
13
13
ns
ns
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
22.5
13
ns
ns
SYNC to SCLK Rising
Edge Setup Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
0
0
ns
ns
t5
t6
t7
Data Setup Time
Data Hold Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
5
5
ns
ns
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
4.5
4.5
ns
ns
24th SCLK Falling Edge to
SYNC Rising Edge
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
0
0
ns
ns
t8
Minimum SYNC HIGH Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
50
33
ns
ns
t9
24th SCLK Falling Edge to
SYNC Falling Edge
VDD = 2.7V to 5.5V
100
ns
NOTES: (1) All input signals are specified with tR = tF = 5ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2. (2) See Serial Write Operation timing
diagram, below. (3) Maximum SCLK frequency is 30MHz at VDD = +3.6V to +5.5V and 20MHz at VDD = +2.7V to +3.6V.
SERIAL WRITE OPERATION
t1
t9
SCLK
SYNC
1
24
t8
t2
t3
t7
t4
t6
t5
DB23
DB0
DB23
DIN
DAC8532
SBAS246A
4
www.ti.com
TYPICAL CHARACTERISTICS
At TA = +25°C, unless otherwise noted.
LINEARITY ERROR AND
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
64
DIFFERENTIAL LINEARITY ERROR vs CODE
64
48
48
32
VDD = VREF = 5V, TA = 25°C,
32
Channel A Output
16
0
16
0
–16
–32
–48
–64
–16
–32
–48
–64
VDD = VREF = 5V, TA = 25°C,
Channel B Output
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
–0.5
–1.0
–1.5
–2.0
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
Digital Input Code
LINEARITY ERROR AND
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
DIFFERENTIAL LINEARITY ERROR vs CODE
64
64
VDD = VREF = 2.7V, TA = 25°C,
48
32
48
32
Channel A Output
16
0
–16
–32
–48
–64
16
0
–16
–32
–48
–64
VDD = VREF = 2.7V, TA = 25°C,
Channel B Output
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
Digital Input Code
ZERO-SCALE ERROR vs TEMPERATURE
FULL-SCALE ERROR vs TEMPERATURE
25
20
15
10
5
15
(To avoid clipping of the output signal
during the test, VREF = VDD – 10mV)
VDD = VREF
VDD = 5V, CH B
10
5
VDD = 5V, CH A
VDD = 2.7V, CH B
VDD = 5V, CH B
0
–5
–10
–15
VDD = 2.7V, CH B
VDD = 2.7V, CH A
VDD = 5V, CH A
VDD = 2.7V, CH A
80 105
0
–40
–10
20
50
–40
–10
20
50
80
105
Temperature (°C)
Temperature (°C)
DAC8532
SBAS246A
5
www.ti.com
TYPICAL CHARACTERISTICS (Cont.)
At TA = +25°C, unless otherwise noted.
ABSOLUTE ERROR
VDD = VREF = 2.7V, TA = 25°C
ABSOLUTE ERROR
30
30
25
VDD = VREF = 5V, TA = 25°C
25
20
20
15
15
10
Channel B Output
10
5
Channel B Output
Channel A Output
5
0
0
–5
–5
–10
–15
–20
–25
–30
–10
–15
–20
–25
–30
Channel A Output
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
Digital Input Code
OUTPUT VOLTAGE DRIFT
HISTOGRAM OF CURRENT CONSUMPTION
2500
VDD = VREF = 5V,
VDD = VREF = 5V, TA = 25°C (±1°C),
Reference Current Included
Digital Code = 7FFFH
2000
1500
1000
500
0
400 440 480 520 560 600 640 680 720 760 800
Time (1min/div)
IDD (µA)
HISTOGRAM OF CURRENT CONSUMPTION
SINK CURRENT CAPABILITY
2500
0.15
0.125
0.1
VDD = VREF = 2.7V,
Reference Current Included
VREF = VDD – 10mV
DAC Loaded with 0000H
2000
1500
1000
500
0
0.075
0.05
0.025
0
VDD = 2.7V
VDD = 5V
280 320 360 400 440 480 520 560 600 640 680
0
1
2
3
4
5
ISINK (mA)
IDD (µA)
DAC8532
SBAS246A
6
www.ti.com
TYPICAL CHARACTERISTICS (Cont.)
At TA = +25°C, unless otherwise noted.
SOURCE CURRENT CAPABILITY
5
SOURCE CURRENT CAPABILITY
2.7
2.65
2.6
4.95
4.9
4.85
2.55
2.5
VREF = VDD – 10mV
DAC Loaded with FFFFH
VREF = VDD – 10mV
DAC Loaded with FFFFH
VDD = 2.7V
VDD = 5V
4.8
0
1
2
3
4
5
0
1
2
3
4
5
ISOURCE (mA)
ISOURCE (mA)
SUPPLY CURRENT vs TEMPERATURE
VDD = VREF = 5V
SUPPLY CURRENT vs DIGITAL INPUT CODE
VDD = VREF = 5V
700
600
500
400
300
200
100
0
700
600
500
400
300
200
100
0
VDD = VREF = 2.7V
VDD = VREF = 2.7V
Reference Current Included,
CH A and CH B Active, No Load
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
–40
–10
20
50
80
105
Temperature (°C)
Digital Input Code
SUPPLY CURRENT vs SUPPLY VOLTAGE
POWER-DOWN CURRENT vs SUPPLY VOLTAGE
Reference Current Excluded
800
50
45
40
35
30
25
20
15
10
5
VREF = VDD, Both DACs Active,
Reference Current Included, No Load
750
700
650
600
550
500
450
400
TA = +105°C
TA = –40°C
TA = +25°C
0
2.7
3.05
3.4
3.75
4.1
4.45
4.8
5.15
5.5
2.7
3.4
4.1
DD (V)
4.8
5.5
VDD (V)
V
DAC8532
SBAS246A
7
www.ti.com
TYPICAL CHARACTERISTICS (Cont.)
At TA = +25°C, unless otherwise noted.
FULL-SCALE SETTLING TIME
(Large Signal)
SUPPLY CURRENT vs LOGIC INPUT VOLTAGE
1150
TA = 25°C, SYNC Input (All Other Inputs = GND)
VDD = VREF = 5V,
5
4
3
2
1
0
Reference Current Included,
Output Loaded with
2kΩ and 200pF to
GND
1050
CHA and CHB Active,
No Load
950
850
VDD = VREF = 5V
750
650
550
VDD = VREF = 2.7V
450
0
1
2
3
4
5
Time (2µs/div)
VLOGIC (V)
HALF-SCALE SETTLING TIME
(Large Signal)
FULL-SCALE SETTLING TIME
(Large Signal)
3
2.5
2
3.5
3
VDD = VREF = 5V,
Output Loaded with
2kΩ and 200pF
to GND.
VDD = VREF = 2.7V,
Output Loaded with
2kΩ and 200pF
to GND.
2.5
2
1.5
1
1.5
1
0.5
0
0.5
0
Time (2µs/div)
Time (2µs/div)
HALF-SCALE SETTLING TIME
(Large Signal)
POWER-ON RESET TO ZERO-SCALE
Loaded with 2kΩ to GND
VDD (2V/div)
VDD = VREF = 2.7V,
Output Loaded with
2kΩ and 200pF
to GND.
1.5
1
VOUT (1V/div)
0.5
0
Time (2µs/div)
Time (100µs/div)
DAC8532
SBAS246A
8
www.ti.com
TYPICAL CHARACTERISTICS (Cont.)
At TA = +25°C, unless otherwise noted.
OUTPUT GLITCH
(Worst Case)
EXITING POWER-DOWN MODE
4.72
4.7
5.5
VDD = VREF = 5V
Power Up to Code FFFFH
5
4.5
4
4.68
4.66
4.64
4.62
4.6
3.5
3
2.5
2
1.5
1
4.58
4.56
4.54
4.52
VDD = VREF = 5V
Code F000H to EFFFH to F000H
(Glitch Occurs Every N • 4096 Code Boundary)
0.5
0
–0.5
Time (1µs/div)
Time (1µs/div)
OUTPUT GLITCH
(Mid-Scale)
SIGNAL-TO-NOISE RATIO vs OUTPUT FREQUENCY
VDD = 5V
2.54
96
94
92
90
88
86
84
2.52
2.5
VDD = 2.7V
2.48
2.46
VDD = VREF = 5V
Code 8000H to 7FFFH to 8000H
(Glitch Occurs Every N • 4096 Code Boundary)
VDD = VREF
–1dB FSR Digital Input, FS = 52ksps
Measurement Bandwidth = 20kHz
2.44
2.42
0
500 1000 1500 2000 2500 3000 3500 4000
Output Frequency (Hz)
Time (1µs/div)
TOTAL HARMONIC DISTORTION
vs OUTPUT FREQUENCY
0
–20
VDD = VREF = 5V
–1dB FSR Digital Input, FS = 52ksps
Measurement Bandwidth = 20kHz
–40
THD
–60
–80
3rd Harmonic
2nd Harmonic
–100
–120
0
500 1000 1500 2000 2500 3000 3500 4000
Output Frequency (Hz)
DAC8532
SBAS246A
9
www.ti.com
THEORY OF OPERATION
VREF
DAC SECTION
RDIVIDER
The architecture of each channel of the DAC8532 consists of
a resistor string DAC followed by an output buffer amplifier.
Figure 1 shows a simplified block diagram of the DAC
architecture.
VREF
2
R
VREF
To Output
Amplifier
(2x Gain)
R
REF (+)
DAC Register
VOUT
X
Resistor String
REF(–)
Output
Amplifier
GND
FIGURE 1. DAC8532 Architecture.
R
R
The input coding for each device is unipolar straight binary,
so the ideal output voltage is given by:
D
VOUTX = VREF
•
65536
where D = decimal equivalent of the binary code that is
loaded to the DAC register; it can range from 0 to 65535.
FIGURE 2. Resistor String.
VOUTX refers to channel A or B.
The write sequence begins by bringing the SYNC line LOW.
Data from the DIN line is clocked into the 24-bit shift register
on each falling edge of SCLK. The serial clock frequency can
be as high as 30MHz, making the DAC8532 compatible with
high speed DSPs. On the 24th falling edge of the serial clock,
the last data bit is clocked into the shift register and the
programmed function is executed (i.e., a change in Data
Buffer contents, DAC Register contents, and/or a change in
the power-down mode of a specified channel or channels).
RESISTOR STRING
The resistor string section is shown in Figure 2. It is simply
a divide-by-2 resistor followed by a string of resistors, each
of value R. The code loaded into the DAC register deter-
mines at which node on the string the voltage is tapped off.
This voltage is then applied to the output amplifier by closing
one of the switches connecting the string to the amplifier.
OUTPUT AMPLIFIER
At this point, the SYNC line may be kept LOW or brought
HIGH. In either case, the minimum delay time from the 24th
falling SCLK edge to the next falling SYNC edge must be met
in order to properly begin the next cycle. To assure the
lowest power consumption of the device, care should be
taken that the digital input levels are as close to each rail as
possible. (Please refer to the “Typical Characteristics” sec-
tion for the “Supply Current vs Logic Input Voltage” transfer
characteristic curve).
Each output buffer amplifier is capable of generating rail-to-
rail voltages on its output which approaches an output range
of 0V to VDD (gain and offset errors must be taken into
account). Each buffer is capable of driving a load of 2kΩ in
parallel with 1000pF to GND. The source and sink capabili-
ties of the output amplifier can be seen in the typical charac-
teristics.
SERIAL INTERFACE
The DAC8532 uses a 3-wire serial interface (SYNC, SCLK,
and DIN), which is compatible with SPI™, QSPI™, and
Microwire™ interface standards, as well as most DSPs. See
the Serial Write Operation timing diagram for an example of
a typical write sequence.
SPI and QSP are registered trademarks of Motorola.
Microwire is a registered trademark of National Semiconductor.
DAC8532
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INPUT SHIFT REGISTER
are set to zero-scale; they remain there until a valid write
sequence and load command is made to the respective
DAC channel. This is useful in applications where it is
important to know the state of the output of each DAC
output while the device is in the process of powering up.
The input shift register of the DAC8532 is 24 bits wide (see
Figure 5) and is made up of 8 control bits (DB16-DB23) and 16
data bits (DB0-DB15). The first two control bits (DB22 and
DB23) are reserved and must be “0” for proper operation. LD
A (DB20) and LD B (DB21) control the updating of each analog
output with the specified 16-bit data value or power-down
command. Bit DB19 is a “Don't Care” bit which does not affect
the operation of the DAC8532 and can be 1 or 0. The following
control bit, Buffer Select (DB18), controls the destination of the
data (or power-down command) between DAC A and DAC B.
The final two control bits, PD0 (DB16) and PD1 (DB17), select
the power-down mode of one or both of the DAC channels. The
four modes are normal mode or any one of three power-down
modes. A more complete description of the operational modes
of the DAC8532 can be found in the Power-Down Modes
section. The remaining sixteen bits of the 24-bit input word
make up the data bits. These are transferred to the specified
Data Buffer or DAC Register, depending on the command
issued by the control byte, on the 24th falling edge of SCLK.
Please refer to Tables II and III for more information.
No device pin should be brought high before power is
applied to the device.
POWER-DOWN MODES
The DAC8532 utilizes four modes of operation. These modes
are accessed by setting two bits (PD1 and PD0) in the control
register and performing a “Load” action to one or both DACs.
Table I shows how the state of the bits correspond to the
mode of operation of each channel of the device. (Each DAC
channel can be powered down simultaneously or indepen-
dently of each other. Power-down occurs after proper data is
written into PD0 and PD1 and a “Load” command occurs.)
Please refer to the "Operation Examples" section for addi-
tional information.
PD1 (DB17) PD0 (DB16)
OPERATING MODE
0
—
0
0
—
1
Normal Operation
Power-Down Modes
Resistor
String DAC
Output Typically 1kΩ to GND
Output Typically 100kΩ to GND
High Impedance
Amplifier
VOUTX
1
0
1
1
TABLE I. Modes of Operation for the DAC8532.
Power-down
Circuitry
Resistor
Network
When both bits are set to 0, the device works normally with
a typical power consumption of 500µA at 5V. For the three
power-down modes, however, the supply current falls to
200nA at 5V (50nA at 3V). Not only does the supply current
fall but the output stage is also internally switched from the
output of the amplifier to a resistor network of known values.
This has the advantage that the output impedance of the
device is known while it is in power-down mode. There are
three different options for power-down: The output is con-
nected internally to GND through a 1kΩ resistor, a 100kΩ
resistor, or it is left open-circuited (High-Impedance). The
output stage is illustrated in Figure 3.
FIGURE 3. Output Stage During Power-Down (High-Impedance)
SYNC INTERRUPT
In a normal write sequence, the SYNC line is kept LOW for
at least 24 falling edges of SCLK and the addressed DAC
register is updated on the 24th falling edge. However, if
SYNC is brought HIGH before the 24th falling edge, it acts as
an interrupt to the write sequence; the shift register is reset
and the write sequence is discarded. Neither an update of
the data buffer contents, DAC register contents or a change
in the operating mode occurs (see Figure 4).
All analog circuitry is shut down when the power-down mode
is activated. Each DAC will exit power-down when PD0 and
PD1 are set to 0, new data is written to the Data Buffer, and
the DAC channel receives a “Load” command. The time to
exit power-down is typically 2.5µs for VDD = 5V and 5µs for
VDD = 3V (See the Typical Characteristics).
POWER-ON RESET
The DAC8532 contains a power-on reset circuit that con-
trols the output voltage during power-up. On power-up, the
DAC registers are filled with zeros and the output voltages
DAC8532
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24th Falling
Edge
24th Falling
Edge
SCLK
SYNC
1
2
1
2
Invalid Write-Sync Interrupt:
Valid Write -Buffer/DAC Update:
SYNC HIGH before 24th Falling Edge
SYNC HIGH after 24th Falling Edge
D
DB23 DB22
DB0
DB23 DB22
DB1 DB0
IN
FIGURE 4. Interrupt and Valid SYNC Timing.
DB23
DB12
D12
0
0
LDB
D9
LDA
D8
X
Buffer Selec
D6
t
PD1
PD0
D4
D15
D3
D14
D2
D13
D1
DB11
D11
DB0
D0
D10
D7
D5
FIGURE 5. DAC8532 Data Input Register Format.
D15
D14
D13-D0
D23
D22
D21
D20
D19
D18
D17
D16
DESCRIPTION
MSB MSB-1 MSB-2...LSB
Reserved Reserved Load B Load A Don’t Care Buffer Select PD1
PD0
(Always Write 0)
0 = A, 1 = B
0
0
0
0
0
0
0
0
0
0
0
1
X
X
X
#
#
#
0
0
Data
X
WR Buffer # w/Data
(see Table III)
WR Buffer # w/Power-Down Command
WR Buffer # w/Data and Load DAC A
0
0
Data
WR Buffer A w/Power-Down Command and LOAD DAC A
(DAC A Powered Down)
(see Table III)
(see Table III)
0
0
0
1
X
0
X
0
0
0
0
0
0
0
1
1
1
0
0
X
X
X
1
#
0
X
Data
X
WR Buffer B w/Power-Down Command and LOAD DAC A
WR Buffer # w/Data and Load DAC B
0
0
(see Table III)
WR Buffer A w/Power-Down Command and LOAD DAC B
X
WR Buffer B w/ Power-Down Command and LOAD DAC B
(DAC B Powered Down)
(see Table III)
0
0
0
0
1
1
0
1
X
X
1
#
0
0
Data
X
WR Buffer # w/Data and Load DACs A and B
WR Buffer A w/Power-Down Command and Load DACs A
and B (DAC A Powered Down)
(see Table III)
(see Table III)
0
0
0
0
1
1
1
1
X
X
0
1
X
WR Buffer B w/Power-Down Command and Load DACs A
and B (DAC B Powered Down)
TABLE II. Control Matrix.
D17
D16
OUTPUT IMPEDANCE POWERDOWN COMMANDS
PD1
PD0
0
1
1
1
0
1
1kΩ
100kΩ
High Impedance
TABLE III. Power-Down Commands.
DAC8532
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OPERATION EXAMPLES
Example 1: Write to Data Buffer A; Write to Data Buffer B; Load DACA and DACB Simultaneously
•
1st—Write to Data Buffer A:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
DB0
0
0
0
0
X
0
0
0
D15
.....
D1
D0
•
2nd—Write to Data Buffer B and Load DAC A and DAC B simultaneously:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
DB0
0
0
1
1
X
1
0
0
D15
.....
D1
D0
The DACA and DACB analog outputs simultaneously settle to the specified values upon completion of the 2nd write sequence.
(The “Load” command moves the digital data from the data buffer to the DAC register at which time the conversion takes place
and the analog output is updated. “Completion” occurs on the 24th falling SCLK edge after SYNC LOW.)
Example 2: Load New Data to DACA and DACB Sequentially
•
1st—Write to Data Buffer A and Load DAC A: DACA output settles to specified value on completion:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
DB0
0
0
0
1
X
0
0
0
D15
.....
D1
D0
•
2nd—Write to Data Buffer B and Load DAC B: DACB output settles to specified value on completion:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
DB0
0
0
1
0
X
1
0
0
D15
.....
D1
D0
After completion of the 1st write cycle, the DACA analog output settles to the voltage specified; upon completion of write cycle 2,
the DACB analog output settles.
Example 3: Power-Down DACA to 1kΩ and Power-Down DACB to 100kΩ Simultaneously
•
1st—Write power-down command to Data Buffer A:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
Don’t Care
DB0
DB0
0
0
0
0
X
0
0
1
•
2nd—Write power-down command to Data Buffer B and Load DACA and DACB simultaneously:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
Don’t Care
0
0
1
1
X
1
1
0
The DACA and DACB analog outputs simultaneously power-down to each respective specified mode upon completion of the
2nd write sequence.
Example 4: Power-Down DACA and DACB to High Impedance Sequentially:
•
1st—Write power-down command to Data Buffer A and Load DAC A: DAC A output = High-Z:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
Don’t Care
DB0
0
0
0
1
X
0
1
1
•
2nd—Write power-down command to Data Buffer B and Load DAC B: DAC B output = High-Z:
Reserved
Reserved
LDB
LDA
DC
Buffer Select
PD1
PD0
DB15
......
DB1
Don’t Care
DB0
0
0
1
0
X
1
1
1
The DACA and DACB analog outputs sequentially power-down to high impedance upon completion of the 1st and 2nd write
sequences, respectively.
DAC8532
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MICROPROCESSOR
INTERFACING
DAC8532(1)
SYNC
68HC11(1)
PC7
DAC8532 to 8051 INTERFACE
Figure 6 shows a serial interface between the DAC8532 and
a typical 8051-type microcontroller. The setup for the inter-
face is as follows: TXD of the 8051 drives SCLK of the
DAC8532, while RXD drives the serial data line of the device.
The SYNC signal is derived from a bit-programmable pin on
the port of the 8051. In this case, port line P3.3 is used. When
data is to be transmitted to the DAC8532, P3.3 is taken LOW.
The 8051 transmits data in 8-bit bytes; thus only eight falling
clock edges occur in the transmit cycle. To load data to the
DAC, P3.3 is left LOW after the first eight bits are transmitted,
then a second and third write cycle is initiated to transmit the
remaining data. P3.3 is taken HIGH following the completion
of the third write cycle. The 8051 outputs the serial data in a
format which presents the LSB first, while the DAC8532
requires its data with the MSB as the first bit received. The
8051 transmit routine must therefore take this into account,
and “mirror” the data as needed.
SCK
SCLK
DIN
MOSI
NOTE: (1) Additional pins omitted for clarity.
FIGURE 8. DAC8532 to 68HC11 Interface.
The 68HC11 should be configured so that its CPOL bit is 0
and its CPHA bit is 1. This configuration causes data appear-
ing on the MOSI output to be valid on the falling edge of SCK.
When data is being transmitted to the DAC, the SYNC line is
held LOW (PC7). Serial data from the 68HC11 is transmitted
in 8-bit bytes with only eight falling clock edges occurring in
the transmit cycle. (Data is transmitted MSB first.) In order to
load data to the DAC8532, PC7 is left LOW after the first
eight bits are transferred, then a second and third serial write
operation is performed to the DAC. PC7 is taken HIGH at the
end of this procedure.
80C51/80L51(1)
P3.3
DAC8532(1)
SYNC
DAC8532 to TMS320 DSP INTERFACE
TXD
RXD
SCLK
DIN
Figure 9 shows the connections between the DAC8532 and
a TMS320 digital signal processor. By decoding the FSX
signal, multiple DAC8532s can be connected to a single
serial port of the DSP.
NOTE: (1) Additional pins omitted for clarity.
FIGURE 6. DAC8532 to 80C51/80L51 Interface.
DAC8532
VDD
Positive Supply
DAC8532 to Microwire INTERFACE
0.1µF
10µF
Figure 7 shows an interface between the DAC8532 and any
Microwire compatible device. Serial data is shifted out on the
falling edge of the serial clock and is clocked into the
DAC8532 on the rising edge of the SK signal.
TMS320 DSP
FSX
SYNC
DIN
VOUT
A
Output A
Output B
DX
V
OUTB
CLKX
SCLK
Reference
Input
VREF
0.1µF
1µF to 10µF
MicrowireTM
CS
DAC8532(1)
SYNC
GND
SCLK
DIN
SK
SO
FIGURE 9. DAC8532 to TMS320 DSP.
NOTE: (1) Additional pins omitted for clarity.
APPLICATIONS
CURRENT CONSUMPTION
Microwire is a registered trademark of National Semiconductor.
The DAC8532 typically consumes 250uA at VDD = 5V and
225uA at VDD = 3V for each active channel, including refer-
ence current consumption. Additional current consumption
can occur at the digital inputs if VIH<<VDD. For most efficient
power operation, CMOS logic levels are recommended at the
digital inputs to the DAC.
In power-down mode, typical current consumption is 200nA.
A delay time of 10 to 20ms after a power-down command is
issued to the DAC is typically sufficient for the power-down
current to drop below 10µA.
FIGURE 7. DAC8532 to Microwire Interface.
DAC8532 to 68HC11 INTERFACE
Figure 8 shows a serial interface between the DAC8532 and
the 68HC11 microcontroller. SCK of the 68HC11 drives the
SCLK of the DAC8532, while the MOSI output drives the
serial data line of the DAC. The SYNC signal is derived from
a port line (PC7), similar to the 8051 diagram.
DAC8532
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DRIVING RESISTIVE AND CAPACITIVE LOADS
For full-scale output swings, the output stage of each
DAC8532 channel typically exhibits less than 100mV of
overshoot and undershoot when driving a 200pF capacitive
load. Code-to-code change glitches are extremely low
(~10uV) given that the code-to-code transition does not
cross an Nx4096 code boundary. Due to internal segmen-
tation of the DAC8532, code-to-code glitches occur at each
crossing of an Nx4096 code boundary. These glitches can
approach 100mVs for N = 15, but settle out within ~2µs.
The DAC8532 output stage is capable of driving loads of up
to 1000pF while remaining stable. Within the offset and gain
error margins, the DAC8532 can operate rail-to-rail when
driving a capacitive load. Resistive loads of 2kΩ can be
driven by the DAC8532 while achieving a typical load regu-
lation of 1%. As the load resistance drops below 2kΩ, the
load regulation error increases. When the outputs of the DAC
are driven to the positive rail under resistive loading, the
PMOS transistor of each Class-AB output stage can enter
into the linear region. When this occurs, the added IR voltage
drop deteriorates the linearity performance of the DAC. This
only occurs within approximately the top 20mV of the DAC’s
digital input-to-voltage output transfer characteristic. The
reference voltage applied to the DAC8532 may be reduced
below the supply voltage applied to VDD in order to eliminate
this condition if good linearity is a requirement at full scale
(under resistive loading conditions).
USING REF02 AS A POWER SUPPLY FOR DAC8532
Due to the extremely low supply current required by the
DAC8532, a possible configuration is to use a REF02 +5V
precision voltage reference to supply the required voltage to
the DAC8532's supply input as well as the reference input, as
shown in Figure 10. This is especially useful if the power
supply is quite noisy or if the system supply voltages are at
some value other than 5V. The REF02 will output a steady
supply voltage for the DAC8532. If the REF02 is used, the
current it needs to supply to the DAC8532 is 567µA typical
and 890µA max for VDD = 5V. When a DAC output is loaded,
the REF02 also needs to supply the current to the load. The
total typical current required (with a 5kΩ load on a given DAC
CROSSTALK AND AC PERFORMANCE
The DAC8532 architecture uses separate resistor strings for
each DAC channel in order to achieve ultra-low crosstalk
performance. DC crosstalk seen at one channel during a full-
scale change on the neighboring channel is typically less than
0.5LSBs. The AC crosstalk measured (for a full-scale, 1kHz
sine wave output generated at one channel, and measured at
the remaining output channel) is typically under –100dB.
In addition, the DAC8532 can achieve typical AC perfor-
mance of 96dB SNR (Signal-to-Noise Ratio) and 65db THD
(Total Harmonic Distortion), making the DAC8532 a solid
choice for applications requiring low SNR at output frequen-
cies at or below 4kHz.
output) is:
567µA + (5V/5kΩ) = 1.567mA
+15
+5V
REF02
1.567mA
OUTPUT VOLTAGE STABILITY
The DAC8532 exhibits excellent temperature stability of
5ppm/°C typical output voltage drift over the specified tem-
perature range of the device. This enables the output voltage
of each channel to stay within a ±25µV window for a ±1°C
ambient temperature change.
V
DD, VREF
SYNC
SCLK
DIN
3-Wire
Serial
Interface
VOUT = 0V to 5V
DAC8532
Good Power-Supply Rejection Ratio (PSRR) performance
reduces supply noise present on VDD from appearing at the
outputs to well below 10µV-s. Combined with good DC noise
performance and true 16-bit differential linearity, the DAC8532
becomes a perfect choice for closed-loop control applica-
tions.
FIGURE 10. REF02 as a Power Supply to the DAC8532.
The load regulation of the REF02 is typically 0.005%/mA,
which results in an error of 392µV for the 1.5mA current
drawn from it. This corresponds to a 5.13LSB error for a 0V
to 5V output range.
SETTLING TIME AND OUTPUT
GLITCH PERFORMANCE
Settling time to within the 16-bit accurate range of the
DAC8532 is achievable within 10µs for a full-scale code
change at the input. Worst case settling times between
consecutive code changes is typically less than 2µs, en-
abling update rates up to 500ksps for digital input signals
changing code-to-code. The high-speed serial interface of
the DAC8532 is designed in order to support these high
update rates.
BIPOLAR OPERATION USING THE DAC8532
The DAC8532 has been designed for single-supply opera-
tion but a bipolar output range is also possible using the
circuit in Figure 11. The circuit shown will give an output
voltage range of ±VREF. Rail-to-rail operation at the amplifier
output is achievable using an amplifier such as the OPA703,
see Figure 11.
DAC8532
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R2
+5V
10kΩ
+5V
OPA703
–5V
R1
10kΩ
VOUT
X
±5V
VDD, VREF
DAC8532
10µF
0.1µF
(Other pins omitted for clarity.)
FIGURE 11. Bipolar Operation with the DAC8532.
The output voltage for any input code can be calculated as
follows:
Due to the single ground pin of the DAC8532, all return
currents, including digital and analog return currents for the
DAC, must flow through a single point. Ideally, GND would
be connected directly to an analog ground plane. This plane
would be separate from the ground connection for the digital
components until they were connected at the power entry
point of the system.
D
R1 + R2
R2
R1
VOUTX = VREF
•
•
– VREF •
65536
R1
where D represents the input code in decimal (0–65535).
With VREF = 5V, R1 = R2 = 10kΩ:
The power applied to VDD should be well regulated and low
noise. Switching power supplies and DC/DC converters will
often have high-frequency glitches or spikes riding on the
output voltage. In addition, digital components can create
similar high-frequency spikes as their internal logic switches
states. This noise can easily couple into the DAC output
voltage through various paths between the power connec-
tions and analog output.
10 • D
VOUTX =
– 5V
65536
This is an output voltage range of ±5V with 0000H corre-
sponding to a –5V output and FFFFH corresponding to a +5V
output. Similarly, using VREF = 2.5V, a ±2.5V output voltage
range can be achieved.
As with the GND connection, VDD should be connected to a
positive power-supply plane or trace that is separate from the
connection for digital logic until they are connected at the
power entry point. In addition, a 1µF to 10µF capacitor in
parallel with a 0.1µF bypass capacitor is strongly recom-
mended. In some situations, additional bypassing may be
required, such as a 100µF electrolytic capacitor or even a
“Pi” filter made up of inductors and capacitors—all designed
to essentially low-pass filter the supply, removing the high-
frequency noise.
LAYOUT
A precision analog component requires careful layout, ad-
equate bypassing, and clean, well-regulated power supplies.
The DAC8532 offers single-supply operation, and it will often
be used in close proximity with digital logic, microcontrollers,
microprocessors, and digital signal processors. The more
digital logic present in the design and the higher the switch-
ing speed, the more difficult it will be to keep digital noise
from appearing at the output.
DAC8532
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PACKAGE DRAWING
DGK (R-PDSO-G8)
PLASTIC SMALL-OUTLINE PACKAGE
0,38
0,25
M
0,65
8
0,08
5
0,15 NOM
3,05
2,95
4,98
4,78
Gage Plane
0,25
0°–6°
1
4
0,69
3,05
2,95
0,41
Seating Plane
0,10
0,15
0,05
1,07 MAX
4073329/C 08/01
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash or protrusion.
D. Falls within JEDEC MO-187
DAC8532
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PACKAGE OPTION ADDENDUM
www.ti.com
3-Oct-2003
PACKAGING INFORMATION
ORDERABLE DEVICE
STATUS(1)
PACKAGE TYPE
PACKAGE DRAWING
PINS
PACKAGE QTY
DAC8532IDGK
ACTIVE
ACTIVE
VSSOP
VSSOP
DGK
DGK
8
8
80
DAC8532IDGKR
2500
(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.
IMPORTANT NOTICE
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enhancements, improvements, and other changes to its products and services at any time and to discontinue
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TI warrants performance of its hardware products to the specifications applicable at the time of sale in
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TI assumes no liability for applications assistance or customer product design. Customers are responsible for
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16-BIT SINGLE CHANNEL, PARALLEL INPUT DIGITAL-TO-ANALOG CONVERTER WITH RAIL VOLTAGE OUTPUT
TI
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