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Problem with Using 2 Analog Inputs of AD7710

Question asked by hosein1122 on Dec 22, 2011
Latest reply on Jan 5, 2012 by MaryMc

Hello, I am Using a single AD7710, to have an accurate Voltmeter and Ammeter.

AIN1 is for Voltmeter and AIN2 for Ammeter.

AD7710 is in 16 bit,Bipolar mode, Gain=1.

Vbios=AGND=0V,      AVDD=5 V,     VSS=-5 V,     REF(+)-REF(-)=2.56 V,     DGND=0v,     DVdd=5V

1-Should I Connect DGND to AGND?

1.JPG

And 2 AD7710 analog inputs here:

2.jpg

The Problem is Shown In the Following Pic:

4.JPG

2-As shown in above table, in test 3, where I use both AIN2 and AIN1 simultaneously, output data in AD7710 and also commercial Voltmeter shows wrong values!! please Help!

for testing I am using the following Variable Current and Voltage Source:

3.jpg

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