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AD9257 Handling of the VCM pin

Question asked by Tak-8810 on Sep 29, 2014
Latest reply on Sep 29, 2014 by Tak-8810

Hello support team,


This thread is one that is related to the AA.

I've created a new discussion for the following questions.

Please advice the these questions.


When I power down the VCM pin by Register 0x102;

1.  We don't need continue to decouple-to-ground with a 0.1uF capacitor. Is this correct?

2.  1.1V is connected to the VCM pin now. Does this cause that cause problems?

      We have designed a circuit to enter the common-mode voltage to the VCM pin already.

      Therefore, we would like to know whether this circuit must be changed.


3.  It is written with Common-mode Range = 0.5V - 1.3V in the data sheet.

     When common-mode voltage is 1.1V, we enter analog input signal with an amplitude of 0.6V-1.6V.  Does this 

     reduce the performance of the ADC? (because it is not within the common mode range)

     Or, does this meet the specs?