AN-1198
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Software Configurable, 12-Bit Dual-Channel, Unipolar/Bipolar Voltage Output Using
the AD5722R DAC
Rev. A | Page 1 of 2
CIRCUIT FUNCTION AND BENEFITS
This circuit provides unipolar and bipolar data conversion using
the AD5722R, a dual, 12-bit, serial input, unipolar/bipolar voltage
output DAC. The only external components needed for this
12-bit DAC are decoupling capacitors on the supply pins and
reference input, leading to savings in cost and board space. This
circuit is well suited for closed-loop servo control applications.
CIRCUIT DESCRIPTION
The AD5722R is a digital-to-analog converter (DAC) that offers
guaranteed 12-bit monotonicity, integral nonlinearity (INL) of
±0.5 LSB, 0.1% total unadjusted error (TUE), and 10 µs settling
time. The AD5722R also integrates a 2.5 V, 5 ppm/°C voltage
reference, reference buffers, and output amplifiers. This leads
to further savings in both cost and board space. Performance
is guaranteed over the following supply voltage ranges: AVDD
supply range from +4.5 V to +16.5 V and AVSS supply range from
−4.5 V to −16.5 V. AVSS can be connected to 0 V if only unipolar
outputs are required. The output range can be individually
programmed for each output channel with these options: 0 V
to +5 V, 0 V to +10 V, 0 V to +10.8 V, −5 V to +5 V, −10 V to
+10 V, and −10.8 V to +10.8 V. The input coding is user selectable
twos complement or offset binary for a bipolar output (depending
on the state of the BIN/
2sCOMP
pin). Coding is straight binary
for a unipolar output. Figure 2 shows that the typical output
error of this circuit at 25°C ambient temperature is less than
0.07 %FSR.
The circuit must be constructed on a multilayer printed circuit
board (PCB) with a large area ground plane. Proper layout,
grounding, and decoupling techniques must be used to achieve
optimum performance (see MT-031 Tutorial, Grounding Data
Converters and Solving the Mystery of AGND and DGND and
MT-101 Tutorial, Decoupling Techniques).
+
AV
SS
–15V
SIG_GND (2)DAC_GND (2)
GND
SDIN
SCLK
SYNC
+5V
A
B
CONTROLLER
SDO
LDAC
CLR
BIN/2sCOMP
10μF
0.1μF
10μF
0.1μF
10μF
0.1μF
V
OUT
A
V
OUT
A
V
OUT
B
V
OUT
B
+
AV
DD
+15V
+
DV
CC
REFIN/REFOUT
0.1μF
AD5722R
+5V
08335-001
Figure 1. Unipolar/Bipolar Configuration for the AD5722R DAC
–0.04
0.08
0
20001000
3000 4000
08335-002
DAC CODE
VOLTAGE OUTPUT ERROR (%FSR)
T
A
= 25°C
–10V TO +10V
–5V TO +5V
0.06
0.04
0.02
0
–0.02
0V TO +5V
0V TO +10V
Figure 2. Voltage Output Error
