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AD1938 with asymmetric input

Question asked by norman on Dec 4, 2015
Latest reply on Dec 7, 2015 by norman

Hello,

 

i was wondering if it is possible to use the input of the AD1938 with an asymmetric input and - for cost condition- with very few input component. The idea is to use only ADC-IN-Pos of the codec and load ADC-IN-Neg to ground. Of course, I've got 1/2 of the input range in that case but it's not the problem.

input.tiff

 

I try it and it's working but i've got a voltage drop on the input of the ADC i cannot explain. in this case R2=R3. Without ADC-IN-P, the divider bridge works fine. with ADC-IN-P, i've got only 80% of the expected value on R2. Am I doing completely wrong ?

thanks for your advice.

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