AD5337ARM datasheet(20/28 Pages) AD

20 / 28 page

AD5337/AD5338/AD5339

Rev. C | Page 20 of 28

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.

GND

SDA

0.1µF

REFIN

10µF

1µF

SCL

VOUTA

VOUTB

VDD =2.5V TO 5.5V

AD780/REF192/ADR391

WITH VDD =5V OR

AD589/AD1580 WITH

VDD =2.5V

AD5337/

AD5338/

AD5339

SERIAL

INTERFACE

EXT

REF

VIN

VOUT

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 can be inaccurate and noisy, the AD5337/AD5338/

AD5339 can 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

10µF

6V TO 12V

AD5339

0.1µF

R1 = 10kΩ

±5V

R2 = 10kΩ

GND

AD1585

+5V

GND

1µF

AD820/

OP295

2-WIRE

SERIAL

INTERFACE

SDA

SCL

REFIN

VOUTB

VOUTA

VDD

VOUT

VIN

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

AD5337ARM датащи(PDF) 20 Page - Analog Devices

AD5337ARM датащи(HTML) 20 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

датащи скачать

ссылки URL