Op amp power supply sequencing question

[Magnus Danielson]

From: "Mike I." <mirwin1 at istar.ca>
Subject: Op amp power supply sequencing question
Date: Fri, 07 Jan 2000 23:33:55 -0500

> Does anyone know whether having different rise-times (and fall-times) 
> for both sides of a +/- 15V supply can damage op amp circuits (eg. when 
> supply is turned on and when supply is turned off).?

I've never hear that it was a real problem for op-amps themselfs. For
electrolytic caps however it is a problem. It's a known problem that quick
steps can make a cap fail, and to help solve that you should shunt them with
a plastic or even ceramic cap. Keep short leads.

I've never experienced opamps to fail. I don't think they are sensitive to the
normal range of rise and fall times that we experience. In either case, caps
should take it down to safe levels anyway.

> I think I read somewhere that  V- should never be applied if V+ is absent
> (even  momentarily). Is this correct?

This may very well be correct for some op-amps. It is really due to the
internal design for a particular op-amp. The only way to know is to read the
datasheet carefully.

Cheers,
Magnus