Q
My customer is looking for an OP- Amp: When the Op-AMP has no power supplied , it must have a high input resistance.
A
Most of our operational amplifiers have very high input impedance, when the power supply is off until a certain voltage. This is due to the fact that there are ESD diodes in the operational amplifier. Kindly find more information on this topic under the following link: http://www.analog.com/library/analogdialogue/archives/42-10/off_amps.html