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.

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.

After reading the datasheet, it was obvious, the AD1938 has 14kohm input and with R2, the divider is different. it can work but it's better with an operational amplifier in front to adjust the impedance.