My 64MHz test failed at 5.00V

I tried at 3.70V and it looks like it IS running. It seems to be running a
little faster. It really is running a little faster - I checked my SPI clock
line with a scope... however... It does not appear to be running at 64MHz.
Maybe 41.8MHz... I'm not sure how reliable it is - but it is running. On
this particular chip it looks like maybe the PLL can't phase lock much above
40MHz? The OSCCON lock bit indicates that the PLL is locked - but it doesn't
look like it to me.

Interesting stuff... but I would never try this in production.

-- Mark

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Electron
> Sent: Tuesday, May 17, 2005 12:32 PM
> To: Microcontroller discussion list - Public.
> Subject: RE: [PIC]: PIC18F at 44.5MHz. Anybody has experiences to share?
>
>
>
> At what voltage were you running it? :)
>
>
> At 11.09 2005.05.17 -0400, you wrote:
> >Hmmm... I have a prototype 18F6585 based device on my desk. Just
> for grins I
> >tried changing the 10MHz xtal to 16MHz (Bumps clock from 40MHz
> to 64MHz) -
> >it didn't work for me :-(  If I can find an 11MHz xtal lying
> around I'll try
> >it at 44MHz.
> >
> >-- Mark
> >
> >> -----Original Message-----
> >> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> >> Of Jinx
> >> Sent: Tuesday, May 17, 2005 9:27 AM
> >> To: Microcontroller discussion list - Public.
> >> Subject: Re: [PIC]: PIC18F at 44.5MHz. Anybody has experiences
> to share?
> >>
> >>
> >> > > Does anybody have experiences to share about overclocking
> >> > > 40MHz-rated PIC18F parts to about 44.5MHz?
> >>
> >> Some time last year I posted about an 18F452 that I accidentally
> >> connected an 18.432MHz xtal to and then turned the PLL on. It
> >> did appear to run OK with some very simple timing tests at
> >> 73.728MHz but I would never expect to try that in production
> >> nd without a complete battery of tests on all the modules it's
> >> impossible to say whether it was a fully functional device at that
> >> speed
> >>
> >> Although you've been advised that 44.5MHz is out of spec, that
> >> doesn't necessarily mean it won't work reliably. Just that if it
> >> doesn't you've no one to blame but yourself. I don't know what
> >> Microchip's actual criteria are for specifications at the higher
> >> frequencies, but at the bottom end you probably can overclock
> >> parts. For example, a -04 part is guaranteed to run at 4MHz,
> >> but came from the same batch as -10 parts, and failed the 10MHz
> >> test. So it could run alright at 6MHz or 8MHz
> >>
> >> It might very well be the case that some 40MHz parts will run
> >> at 44.5MHz. You would have to sort out which ones will, and
> >> with the functions you're using
> >>
> >>
> >> --
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> >>
> >>
> >
> >
> >
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