At 08:37 AM 11/16/2005 -0600, you wrote:
> > I'm designing a circuit using a PIC18F452 that is going
> > to communicate through USART at 115200bps. From
> >  the pic datasheet, I calculated that the ideal crystal
> > for my app is 14.7456MHz (or 7.3728MHz, but I'll stick
> > with the faster because I need the extra speed).
>
>I'll take another tack, since you've had a number of
>excellent answers about this from other folks...
>
>Have you considered a three-pin ceramic resonator?
>Accuracy is sub-crytal (~.5%), but much better than
>internal oscillator or RC network.  Plus, the three pin
>jobs have internal caps, so you just plug it in and go.
>They're also more rugged than crystals.
>
>My favorite is 81-CSTCC3.68MG-TC from Mouser.
>Surface mount.  Run 3.68 into the PLL and you'll
>get 14.72- sound familiar?
>
>Mike H.

Doesn't that violate the maximum HS oscillator period specification of
250ns with PLL active? (Parameter 1/1A) Not that I doubt it usually works...

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
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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