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AD8274 -- how is common-mode voltage defined?

Question asked by cmoreno_uw on Sep 12, 2017
Latest reply on Sep 21, 2017 by krisf

Looking at the specs, in particular figures 8 and 10 on page 6, the common-mode voltage seems to be limited to 25V for +/-15V supplies.

 

My question is:  where is that 25V measured?  At the pins of the IC, or at the inverting and non-inverting input pins of the op-amp?  If the former (which seems reasonable, since the specs are given for the IC), then I cannot understand why if I use it in a gain=1/2 configuration, with +/-15V supplies, the circuit would fail with two identical input voltages of 30V  (the voltage at the input pins of the op-amp would be 10V, which is within the power supplies range).

 

Can you confirm?  (or clarify if there is something I'm misunderstanding?)

 

Thanks,

Carlos

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