AD5337ARM datasheet(20/24 Pages) AD

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AD5337/AD5338/AD5339

Rev. A | Page 20 of 24

APPLICATIONS

TYPICAL APPLICATION CIRCUIT

The AD5337/AD5338/AD5339 can be used with a wide range of

reference voltages for 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, the REF192,

and the ADR391 (2.5 V references). For 2.5 V operation, a

suitable external reference would be the AD589 or AD1580, a

1.23 V band gap reference. Figure 36 shows a typical setup for

the AD5337/AD5338/AD5339 when using an external reference.

Note that A0 can be high or low.

AD5337/

AD5338/

AD5339

GND

SDA

SERIAL

INTERFACE

VOUT

EXT

REF

0.1

µF

REFIN

AD780/REF192/ADR391

WITH VDD = 5V OR

AD589/AD1580 WITH

VDD = 2.5V

VDD = 2.5V TO 5.5V

VIN

µF

SCL

VOUTA

VOUTB

Figure 36. AD5337/AD5338/AD5339 Using External Reference

If an output range of 0 V to VDD is required, the simplest

solution is to connect the reference input to VDD. Because this

supply may be inaccurate and noisy, the AD5337/AD5338/

AD5339 may be powered from a reference voltage, for example,

using a 5 V reference such as the REF195 which provides a

steady output supply voltage. With no load on the DACs, the

REF195 is required to supply 600 µA supply current to the DAC

and 112 µA to the reference input. When the DAC outputs are

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

loads; therefore, the total current required with a 10 kΩ load on

each output is

712 µA + 2(5 V/10 kΩ) = 1.7 mA

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

which results in an error of 3.4 ppm (17 µV) for the 1.7 mA

current drawn from it. This corresponds to a 0.0009 LSB error

at 8 bits and a 0.014 LSB error at 12 bits.

BIPOLAR OPERATION

The AD5337/AD5338/AD5339 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

AD5339

0.1

µF

VDD

VOUTA

R1 = 10k

Ω

±5V

R2 = 10k

Ω

REFIN

GND

VOUT

VIN

AD1585

+5V

2-WIRE

SERIAL

INTERFACE

SCL SDA

VOUTB

GND

µF

Figure 37. Bipolar Operation with the AD5339

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

MULTIPLE DEVICES ON ONE BUS

Figure 38 shows two AD5339 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 four DACs to be written to or

read from independently.

PULL-UP

RESISTORS

SCL

SDA

AD5339

SCL

SDA

VDD

MICROCONTROLLER

Figure 38. Multiple AD5339 Devices on One Bus

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