From: John Woodgate
Subject: Re: Unused op amp inputs
Date: Thu, 19 Dec 2002 20:35:05 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 19 Dec 2002 21:39:46 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Gibbo
wrote (in <firstname.lastname@example.org>) about 'Unused
op amp inputs', on Thu, 19 Dec 2002:
>John Woodgate wrote:
>>>>There should NEVER be an unused input on an op-amp.
>>>Perhaps he refers to a spare op-amp in a quad package. That would have *two*
>>Well, tell him what to do with them, then! Inverting input tied to
>>output, non-inverting input to ground.
>>This works for both bipolar and CMOS devices.
>But does it always give the lowest current consumption ?
If you want to explore special configurations to minimise supply
current, you have to read the data sheet for the device you are using.
My scheme works (for all op-amps AFAIK) in the sense that no
misbehaviour will occur (excess current, oscillation, smoke), and the
supply current is the zero-signal current, which is usually the minimum
unless there is a 'sleep' pin.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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