AnsweredAssumed Answered

AD8422 output set zero with 1M-ohm serial register

Question asked by madraccoon on Aug 22, 2016
Latest reply on Sep 15, 2016 by Emman.A

Hi, I'm wonyoung.


I want to use AD8422 with voltage dividing with high impedance register(1Mohm).


Here's circuit i want to use.



I tested this circuit for performance test, It doesn't work when R23 and R27 set above 300K-ohm. Under 200K-ohm, it works normally. Here's the result of test


I want to set R23 and R27 as 1M-ohm for sensor measurement.


Here's my Questions.


1) Why this result came out?

2) Is any way to use 1M ohm serial register with AD8422? Like above circuit?

3) If I can't use AD8422 with 1Mohm serial register, Can you recommand other Instrumentation Amplifier, which can use with 1Mohm serial register?


Best regards