AN-1202
APPLICATION NOTE
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Simplified 12-Bit Voltage and 4 mA-to-20 mA Output Solution
Using the AD5412
CIRCUIT FUNCTION AND BENEFITS
CIRCUIT DESCRIPTION
This circuit provides unipolar/bipolar voltage and 4 mA-to20 mA outputs using the AD5412, a single channel, 12-bit,
serial input, unipolar/bipolar voltage and 4 mA-to-20 mA
current source DAC. This circuit utilizes only the AD5412
product. The only external components needed are decoupling
capacitors on the supply pins and reference input and a pull-up
resistor for the open-drain FAULT output, which alerts to a loss
of compliance voltage on the current output or an overtemperature
of the AD5412 device. This solution offers a level of integration
that leads to savings in both cost and board space. This circuit is
well suited for both programmable logic controllers (PLCs) and
distributed control systems (DCSes) in industrial control
applications.
The AD5412 is a low cost, precision, highly integrated 12-bit
digital-to-analog converter offering a programmable current
source and a programmable voltage output designed to meet the
requirements of industrial process control applications. The
voltage output range can be programmed at 0 V to +5 V, 0 V to
+10 V, −5 V to +5 V, or −10 V to +10 V. The current output, which
is accessed from a separate pin, can be programmed with the
ranges of 4 mA to 20 mA, 0 mA to 20 mA, or 0 mA to 24 mA.
The AD5412 contains an internal 5 V, 10 ppm/°C maximum
voltage reference. This leads to further savings in both cost and
board space. Operation is specified with an AVDD supply up to
24 V and an AVSS supply up to −24 V. However, the AD5412 is
+
+15V
0.1µF
10µF
0.1µF
CCOMP
AVDD
DVCC DVCC
SELECT
+VSENSE
CLEAR
SELECT
AD5412
VOUT
CLEAR
–VSENSE
LATCH
SCLK
BOOST
SDIN
IOUT
FAULT
SDO
GND AVSS REFOUT REFIN RSET
VOUT
IOUT
0.1µF
+
10µF
0.1µF
–15V
Figure 1. Configuration of the AD5412
(Simplified Schematic)
Rev. A | Page 1 of 2
08354-001
CONTROLLER
10kΩ
AN-1202
Application Note
LEARN MORE
capable of operating with an AVDD supply of up to 40 V. The
AD5412 contains an on-chip regulated 4.5 V output (DVCC pin)
capable of sourcing up to 5 mA. This can be used as a termination
for pull-up resistors or to power digital circuitry, eliminating
the need to generate a logic power supply.
Kester, Walt. 2005. The Data Conversion Handbook. Analog
Devices. Chapters 3 and 7.
Figure 2 and Figure 3 show that the typical accuracy of this
circuit at 25°C ambient temperature is better than 0.011% for
both current and voltage outputs.
MT-031 Tutorial, Grounding Data Converters and Solving the
Mystery of AGND and DGND. Analog Devices.
The circuit must be constructed on a multilayer PC board with
a large area ground plane. Proper layout, grounding, and
decoupling techniques must be used to achieve optimum
performance (see Tutorial MT-031, Grounding Data Converters
and Solving the Mystery of "AGND" and "DGND," and Tutorial
MT-101, Decoupling Techniques).
MT-015 Tutorial, Basic DAC Architectures II: Binary DACs.
Analog Devices.
MT-101 Tutorial, Decoupling Techniques. Analog Devices.
Voltage Reference Wizard Design Tool.
Data Sheets and Evaluation Boards
AD5412 Data Sheet.
AD5422 Evaluation Board (Compatible with AD5412).
REVISION HISTORY
0.010
4/13—Rev. 0 to Rev. A
4mA TO 20mA
0mA TO 20mA
0mA TO 24mA
0.005
Changed Document Title from CN-0097 to
AN-1202 .............................................................................. Universal
0
7/09—Revision 0: Initial Version
–0.005
–0.010
TA = 25°C
RLOAD = 250Ω
–0.015
08354-002
CURRENT OUTPUT ERROR (%FSR)
0.015
–0.020
0
1000
2000
DAC CODE
3000
4000
Figure 2. Current Output Accuracy
0.005
0.001
–0.001
–0.003
0V TO +5V
0V TO +10V
–5V TO +5V
–10V TO +10V
–0.005
–0.007
–0.009
–0.011
TA = 25°C
08354-003
VOLTAGE OUTPUT ERROR (%FSR)
0.003
–0.013
–0.015
0
1000
2000
DAC CODE
3000
4000
Figure 3. Voltage Output Accuracy
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AN08354-0-4/13(A)
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