At 06:40 PM 3/11/99 +0000, you wrote:
>Hi,
>
>On 12 Mar 99 at 0:15, Nicholas Uloth wrote:
><snip>
>> Has anyone else been running pics at low temperatures - did you do anything
>> special for the
>> oscillator circuit ?
>
>I've just ran a sample of my boards (12C508 industrial temp range)
>through the 50C to -10C temperature range, quickly.  They run fine.
>I have run them before down to -25C with no detectable problems.
>Some previous version of the same circuit ran outdoors in Antarctica
>(-30C to -40C) and our customer thinks it worked fine....

what voltage were you running at ?  The tricky thing is that it looks like
the problem
is due to temperature related changes inside the pic - because the problem
also occurs when I only cool
the uP and leave the oscillator circuit at room temp.


>Are you using NPO capacitors on the crystal?
yep

>Do you use a series drive limit resistor?
yes 100k

>What does your crystal's datasheet say?
Its rated to -40C, im using 10pF load caps instead of the recomended 12.5pF.


Nic