----- Original Message -----
From: "Herbert Graf" <mailinglist@FARCITE.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, January 20, 2002 4:23 PM
Subject: Re: [PIC]: Expected life of a pic?


> > I have bulit a small circuit with a 12C508 that is intended to
> > run continuously.  The chip runs an endless loop.
> >
> > If I had built this with 'conventional' parts (ie. 555 timer and
> > gates), I would not be worried about it running for years and years.
> >
> > Does the fact that a PIC is a processor shorten its life?  Or can
> > I reasonably expect this to run 'forever'?
>
>         My guess is that the limiting factor of a PIC for longevity is the
amount
> of time the PROM stays correct. I don't know what the stats are on a OTP
> chip but I know with FLASH parts life times are usually in the 10 to 15
year
> range. I'd have to say that in most circumstances most other parts of the
> circuit (ie. electrolytic caps, transformers, etc.) would die long before
> the PIC. TTYL

I think the time it takes for the charge to leak out of the memory cells
would be the limiting factor. I have analog audio equipment from the 1970s
that still works OK, but I suppose the aluminum electrolytics are losing
capacity too. My digital stuff became totally obsolete before I could test
its longevity. Stress like high voltage and temperature severely limit the
lifetime. Not many TVs still work from 30 yrs ago.
/\/\/\/*=Martin

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