AD5322 datasheet(14/16 Pages) AD

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REV. 0

AD5302/AD5312/AD5322

–14–

1 F

VREFA

VREFB

SCLK

DIN

SYNC

VDD

GND

VOUTA

VOUTB

+6V TO +16V

SERIAL

INTERFACE

VOUT

VIN

GND

REF195

0.1 F

10 F

AD5302/AD5312/

AD5322

Figure 37. Using an REF195 as Power and Reference to

the AD5302/AD5312/AD5322

Bipolar Operation Using the AD5302/AD5312/AD5322

The AD5302/AD5312/AD5322 has been designed for single

supply operation, but bipolar operation is also achievable using

the circuit shown in Figure 38. The circuit shown has been config-

ured to achieve an output voltage range of –5 V < VOUT < +5 V.

Rail-to-rail operation at the amplifier output is achievable using

an AD820 or OP295 as the output amplifier.

1 F

VREFA/B

SCLK

DIN

SYNC

VDD

GND

VOUTA/B

0.1 F

10 F

VDD = +5V

VOUT

VIN

GND

REF

195

SERIAL

INTERFACE

AD820/

OP295

+5V

–5V

10k

AD5302/AD5312/

AD5322

+6V TO +16V

Figure 38. Bipolar Operation Using the AD5302/AD5312/

AD5322

The output voltage for any input code can be calculated as

follows:

VOUT = [(VREF × D/2

× (R1+R2)/R1 – V

REF × (R2/R1)]

where

D is the decimal equivalent of the code loaded to the DAC

N is the DAC resolution

VREF is the reference voltage input.

with

VREF = 5 V

R1 = R2 = 10 k

Ω and V

DD = 5 V

VOUT = (10

× D/2N) – 5 V

Opto-Isolated Interface for Process Control Applications

The AD5302/AD5312/AD5322 has a versatile 3-wire serial

interface, making it ideal for generating accurate voltages in

process control and industrial applications. Due to noise, safety

requirements or distance, it may be necessary to isolate the

AD5302/AD5312/AD5322 from the controller. This can easily

be achieved by using opto-isolators, which will provide isolation

in excess of 3 kV. The serial loading structure of the AD5302/

AD5312/AD5322 makes it ideally suited for use in opto-isolated

applications. Figure 39 shows an opto-isolated interface to the

AD5302/AD5312/AD5322 where DIN, SCLK and

SYNC are

driven from opto-couplers. The power supply to the part also

needs to be isolated. This is done by using a transformer. On

the DAC side of the transformer, a +5 V regulator provides the

+5 V supply required for the AD5302/AD5312/AD5322.

VDD

SCLK

10k

AD5302/AD5312/

AD5322

VREFA

DIN

SYNC

VDD

GND

VOUTA

0.1 F

10 F

VREFB

VOUTB

SCLK

+5V

REGULATOR

POWER

VDD

SYNC

10k

VDD

DIN

10k

Figure 39. AD5302/AD5312/AD5322 in an Opto-Isolated

Interface

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