AD5305/AD5315/AD5325

Rev. G | Page 20 of 24

APPLICATIONS

TYPICAL APPLICATION CIRCUIT

The AD5305/AD5315/AD5325 can be used with a wide range

of reference voltages where the devices offer full, one-quadrant

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 AD5305/

AD5315/AD5325 when using an external reference. Note that

A0 can be high or low.

GND

SDA

0.1µF

REFIN

A0

10µF

1µF

SCL

EXT

REF

AD780/REF192

OR AD589 WITH

AD5305/

AD5315/

AD5325

SERIAL

INTERFACE

Figure 36. AD5305/AD5315/AD5325 Using External Reference

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

AD5305/AD5315/AD5325 can 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 AD5305/

AD5315/AD5325. The typical current required from the

REF195 is 600 μA supply current and approximately 112 μA

into the reference input. 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

712 μA + 4(5 V/10 kΩ) = 2.70 mA

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

which results in an error of 5.4 ppm (27 μV) for the 2.7 mA

current drawn from it. This corresponds to a 0.0014 LSB error

at eight bits and 0.022 LSB error at 12 bits.

BIPOLAR OPERATION

The AD5305/AD5315/AD5325 have been 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

10µF

6V TO 12V

AD5305

0.1µF

R1 = 10kΩ

±5V

R2 = 10kΩ

REFIN

A0

GND

AD1585

1µF

+5V

2-WIRE

SERIAL

INTERFACE

GND SCL SDA

AD820/

OP295

Figure 37. Bipolar Operation with the AD5305

The output voltage for any input code can be calculated as

follows:

(

)

(

()

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

×

−

+

×

×

=

1

/

2

1

2

1

2

/

R

R

REFIN

R

R

R

D

REFIN

V

N

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

MULTIPLE DEVICES ON ONE BUS

Figure 38 shows two AD5305 devices on the same serial bus.

Each has a different slave address because the state of the A0 pin

is different. This allows each of eight DACs to be written to or

read from independently.

SCL

SDA

AD5305

A0

AD5305

SCL

SDA

A0

MICRO-

CONTROLLER

PULL-UP

RESISTORS

Figure 38. Multiple AD5305 Devices on One Bus