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How to determine attenuation divider for Differential input to AD7264?

Question asked by UtpalT on Aug 17, 2016
Latest reply on Aug 24, 2016 by jcolao

Hello,

 

For our application, we are using AD7264 as input stage.

The AD7264 will be fed with four analogue differential channels:

  1. 0 Vdc to 100 Vdc - two channels
  2. 0 Vdc to 10 Vdc - two channels

 

Datasheet defines two specific values for Vcm range

2 V for PGA = 1

(AVcc / 2) for 2 <= PGA <= 128

 

1. How to identify the "Vcm" run-time?

2. How to design the incoming differential signal attenuator if no Vcm is specified?

3. If Vcm is specified to be zero, how the ADC would handle -ve signal range as per the equation:

Analogue input range = (Vcm) +- (Vref / (2 x Gain)) and single +5 V supply operation?

 

Best regards,

--Utpal

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