Paul Bjork wrote:
>
> Anyone have any experience running a pic down to -60 degrees C?  I
> tried a simple experiment with an externally clock driven PIC16c73
> running a PWM output, all by itself. My can of envirotech chiller
> spray, which says -62 F, killed the PWM output and so, I presume, the
> whole chip.  I haven't yet characterized it accurately below -40 C.
>
> I need a PWM output and a UART, although I could easily emulate them.
> Also an ADC would be nice but not necessary at that temperature.
>
> Is there a temperature range for any Microchip controller below -40 C?
> It would seem that some of the lads driving cars in Iceland would
> appreciate them.


What usually happens with freeze mist is the consequent condensation
causes significant leakage currents.......you need low humidity air to
properly perform such a test.

There are a variety of materials incompatibility issues that become
serious problems below -40C, so regardless of electronic performance, I
agree with suggestion to include a heater.  The high positive tempco
polymeric types are particularly easy to apply.
--

Paul Mathews, consulting engineer
AEngineering Co.
optoeng@whidbey.com
non-contact sensing and optoelectronics specialists