At 04:12 PM 5/16/2005 +0100, you wrote:

>I think the subject says it all.. anyway:
>
>Does anybody have experiences to share about overclocking
>40MHz-rated PIC18F parts to about 44.5MHz?
>I need the PIC to be perfectly in sync with some peripherals
>which must run at an integer fraction of the mentioned MHz.
>
>Is there an ~official test somewhere to test the core for
>reliability? (e.g. there are lotsa x86 utilities of this kind)
>
>What is the best voltage to achieve most stable overclocking?
>My guess is 5.5V but maybe I'm applying too much x86 physics
>here.

Yes, I think that's correct. It might be reasonable to infer
probable correct operation at 10% higher frequency with 5.5V
supply, especially over a limited temperature range. Whether you'd want
to put it into a product is another matter, and it's doubtful that
you can find a way to thoroughly test this at a reasonable cost. You could
do a half-ass check by seeing where your application visibly fails at 4.5V
and then at 5.5V to see what VISIBLE improvement in margin there has been,
but there's no guarantee that there isn't some unforseen process going on
that will cause you grief.

You should also consider using the USB 18F PICs which are
guaranteed to operate at 48MHz and are not particularly expensive.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com




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