I am using an OP4177 in an externally powered application (voltage follower for battery cells). Is it OK to leave the voltage input from the cells connected when the supply power is off?
What is the state of your supplies when it is powered off? Is it grounded or floating?
In general, for as long as the input current is kept to less than 5mA, the part should be ok. The Input Overvoltage section on the datasheet gives guidance on this:
Also, for a good read, you might want to check out this article which goes in depth with power sequencing on amplifiers:
Improper Power Sequencing in Op Amps: Analyzing the Risks | Analog Devices
Please also take a look at the ADA4177. It has higher bandwidth, lower noise, and has integrated overvoltage protection.
Are you using the amplifier to monitor the battery voltage?
I should have said - there is a 1k resistor on the input
Many thanks Kris; that is most helpful. I have a 1k on each input. and the current power-off is about 1 mA. Yes I am using the OP4177 as a voltage follower to monitor battery voltages without drawing power from the cells.