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AD5303/AD5313/AD5323

Rev. B | Page 21 of 28

APPLICATIONS INFORMATION

TYPICAL APPLICATION CIRCUIT

The AD5303/AD5313/AD5323 can be used with a wide range

of reference voltages, especially if the reference inputs are con-

figured to be unbuffered, in which case the devices offer a full,

one-quadrant multiplying capability over a reference range of

0 V to VDD.

More typically, the AD5303/AD5313/AD5323 may be used

with a fixed precision reference voltage. Figure 39 shows a

typical setup for the AD5303/AD5313/AD5323 when using

an external reference. If the reference inputs are unbuffered,

the reference input range is from 0 V to VDD, but if the on-chip

reference buffers are used, the reference range is reduced. Suit-

able references for 5 V operation are the AD780 and REF192

(2.5 V references). For 2.5 V operation, a suitable external

reference is the REF191, a 2.048 V reference.

SCLK

DIN

GND

AD5303/AD5313/

AD5323

SERIAL

INTERFACE

EXT

REF

AD780/REF192

WITH VDD = 5V

OR REF191 WITH

VDD = 2.5V

VOUT

SYNC

VOUTA

VOUTB

VREFA

VREFB

1µF

VDD = 2.5V to 5.5V

VDD

BUF A BUF B

Figure 39. AD5303/AD5313/AD5323 Using External Reference

If an output range of 0 V to VDD is required when the reference

inputs are configured as unbuffered (for example, 0 V to 5 V),

the simplest solution is to connect the reference inputs to VDD.

As this supply may not be very accurate and may be noisy, the

AD5303/AD5313/AD5323 can be powered from the reference

voltage, for example, using a 5 V reference such as the REF195,

as shown in Figure 40. The REF195 outputs a steady supply

voltage for the AD5303/AD5313/AD5323. The supply current

required from the REF195 is 300 μA and approximately 30 μA

or 60 μA into each of the reference inputs (if unbuffered). This

is with no load on the DAC outputs. When the DAC outputs are

loaded, the REF195 also needs to supply the current to the

loads. The total current required (with a 10 kΩ load on each

output) is

360 μA + 2(5 V/10 kΩ) = 1.36 mA

The load regulation of the REF195 is typically 2 ppm/mA, which

results in an error of 2.7 ppm (13.5 μV) for the 1.36 mA current

drawn from it. This corresponds to a 0.0007 LSB error at eight

bits and 0.011 LSB error at 12 bits.

SCLK

DIN

AD5303/AD5313/

AD5323

SERIAL

INTERFACE

REF195

OUTPUT

SYNC

VOUTA

VOUTB

VDD

VREFA

1µF

15V

GND

VREFB

0.1µF

10µF

GND BUF A BUF B

Figure 40. Using an REF195 as Power and Reference to the

AD5303/AD5313/AD5323

BIPOLAR OPERATION USING THE AD5303/

AD5313/AD5323

The AD5303/AD5313/AD5323 have been designed for single-

supply operation, but bipolar operation is also achievable using

the circuit shown in Figure 41. The circuit shown has been con-

figured 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.

SCLK

DIN

AD5303/AD5313/

AD5323

SERIAL

INTERFACE

REF195

SYNC

VOUTA/B

VREFA/B

1µF

GND

6V to 16V

0.1µF

10µF

VDD

VDD = 5V

+5V

–5V

10kΩ

AD820/

OP295

10kΩ

±5V

GND BUF A BUF B

OUTPUT

Figure 41. Bipolar Operation Using the AD5303/AD5313/AD5323

The output voltage for any input code can be calculated as

follows:

[

])

(

)

(

)

(

)

(

REF

OUT

−

where:

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

N is the DAC resolution.

VREF is the reference voltage input, and gain bit = 0, with

VREF = 5 V

R1 = R2 = 10 kΩ and VDD = 5 V,

OUT

)

(

−

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