AD7712 datasheet(27/28 Pages) AD

27 / 28 page

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REV. E

AD7712

CLOCK

GENERATION

SERIAL INTERFACE

OUTPUT

CHARGE-BALANCING A/D

CONVERTER

AUTO-ZEROED

–

MODULATOR

DIGITAL

FILTER

AD7712

AGND DGND

MODE SDATA SCLK

MCLK OUT

MCLK IN

AIN1(+)

AIN1(–)

REF

IN (–)

REF

IN (+)

SYNC

4.5 A

A = 1 – 128

DRDY

TFS

RFS

REF OUT

2.5V REFERENCE

VOLTAGE

ATTENUATION

AIN2

STANDBY

CONTROL

VSS

500

PGA

AVDD

DVDD

ANALOG +5V SUPPLY

VBIAS

4–20mA

LOOP

Figure 21. 4–20 mA Loop Measurement Using the AD7712

APPLICATIONS

4–20 mA LOOP

The AD7712’s high level input can be used to measure the current

in 4–20 mA loop applications as shown in Figure 21. In this

case, the system calibration capabilities of the AD7712 can be

used to remove the offset caused by the 4 mA flowing through

the 500

Ω resistor. The AD7712 can handle an input span as

low as 3.2

× V

REF (= 8 V with a VREF of +2.5 V) even though the

nominal input voltage range for the input is 10 V. Therefore, the

full span of the A/D converter can be used for measuring the

current between 4 mA and 20 mA.

AD7712 Datasheet(PDF) 27 Page - Analog Devices

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