If build a circuit with some filter capacitors (10uF) an the input's of the OpAmp AD8676 and have the problem that after some time (days of power up/down) suddenly the OpAmp start to leak at it's positive input an sink about 4uA.
I'm searching now the problem and got aware of the maximum differential input voltage and the input current limit.
I think the problem comes with the power down sequence and the discharging of the capacitors.
While I measure the signals of both inputs during power down I see up to 5V voltage difference between the inputs.
And here starts my question:
In the datasheet of the AD8676 there is a statement about the Differential Input Voltage of +-0.7V in the "Absolute Maximum Ratings" section.
Does that mean, that I have to make sure that this 0.7V never be exceeded because some protection diodes at the input stage would start to conduct and the 10mA could flow in case of a an input circuit that can source that amount of current? (e.g. my capacitors?)
But how can it be that I see 5V between the inputs in this case? With diodes this should never be possible.
So what exactly does this +-0.7V differential input voltage really mean?
Thanks for any advice