AD5306 datasheet(20/24 Pages) AD

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AD5306/AD5316/AD5326

Rev. F | Page 20 of 24

APPLICATIONS

TYPICAL APPLICATION CIRCUIT

The AD5306/AD5316/AD5326 can be used with a wide range

of reference voltages where the devices offer full one-quadrant

multiplying capability over a reference range of 0 V to VDD.

More typically, these devices are used with a fixed precision-

reference voltage. Suitable 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 AD589, a 1.23 V band gap

reference. Figure 36 shows a typical setup for the AD5306/

AD5316/AD5326 when using an external reference. Note that

A0 and A1 can be high or low.

AD5306/

AD5316/

AD5326

GND

SDA

SERIAL

INTERFACE

VOUT

EXT

REF

0.1

μF

VREFA

VREFC

VREFD

VREFB

AD780/REF192

WITH VDD = 5V

OR AD599 WITH

VDD = 2.5V

VDD = 2.5V TO 5.5V

VIN

μF

SCL

VOUTA

VOUTC

VOUTB

VOUTD

Figure 36. AD5306/AD5316/AD5326

Using a 2.5 V External Reference

DRIVING VDD FROM THE REFERENCE VOLTAGE

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

inputs are configured as unbuffered, the simplest solution is to

connect the reference inputs to VDD. Because this supply may be

noisy and somewhat inaccurate, the AD5306/AD5316/AD5326

may be powered from the reference voltage, for example, using

a 5 V reference such as the REF195. The REF195 outputs a

steady supply voltage for the AD5306/AD5316/AD5326. The

typical current required from the REF195 is 500 μA supply

current and approximately 112 μA to supply 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

612 μA + (5 V/10 kΩ) = 2.6 mA

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

which results in an error of 5.2 ppm (26 μV) for the 2.6 mA

current drawn from it. This corresponds to a 0.0013 LSB error

at eight bits and a 0.021 LSB error at 12 bits.

BIPOLAR OPERATION USING THE

AD5306/AD5316/AD5326

The AD5306/AD5316/AD5326 are designed for single-supply

operation, but a bipolar output range is also possible using the

circuit in Figure 37. This circuit gives an output voltage range

of ±5 V. Rail-to-rail operation at the amplifier output is

achievable using an AD820 or an OP295 as the output amplifier.

+5V

–5V

AD820/

OP295

μF

6V TO 12V

0.1

μF

10k

±5V

10k

GND

VOUT

AD1585

+5V

2-WIRE

SERIAL

INTERFACE

SCL SDA

GND

μF

AD5306/

AD5316/

AD5326

VREFA

VREFC

VREFD

VREFB

VOUTC

VOUTB

VOUTA

VOUTD

VIN

VDD

Figure 37. Bipolar Operation with the AD5306/AD5316/AD5326

The output voltage for any input code can be calculated as follows:

(

) ()

()

REFIN

OUT

−

⎥

⎦

⎤

⎢

⎣

⎡

where:

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

N is the DAC resolution.

REFIN is the reference voltage input.

With REFIN = 5 V, R1 = R2 = 10 kΩ,

VOUT = (10 × D/2N) − 5 V

MULTIPLE DEVICES ON ONE BUS

Figure 38 shows four AD5306 devices on the same serial bus.

Each has a different slave address since the states of the A0 and

A1 pins are different. This allows each of 16 DACs to be written

to or read from independently.

PULL-UP

RESISTORS

SCL

SDA

AD5306

SCL

SDA

VDD

MASTER

SCL

SDA

AD5306

SCL

SDA

Figure 38. Multiple AD5306 Devices on One Bus

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