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OPA1622: Enable pin behavior on input output - Output not off, but clipped

Part Number: OPA1622

Hello All,

I've received a simple unity gain board that I designed and noticed a very odd behavior: when shorting the OPA1622 enable pin to ground, the output is clipped between -1.4V and +1.6V.
It was my understanding that when asserting the enable pin to less than 0.8V the output would become high impedance... was I mistaken?

Just to confirm, can the voltage at the enable pin be lower than GND, and higher than VEE?

Thanks a lot for your answers

  • Hello, 

    The output stage transistors are turned off but the output stage shouldn't be considered to be in high impedance. The schematic below shows that the enable pin is diode protected to VCC and VEE and should not go beyond either. Do you have PCB schematic you can share for our review? Can you share the conditions the device is under for power supply, common mode, output load etc?

    Best Regards, 

    Chris Featherstone