M.Schmaeche wrote:
>
> as PIC controllers are offered with automotive temperature range
> (-40...+125 degrees Celsius) I think there are some people out there who
> have used them and have already experience where to get appropriate
> crystals or resonators for this temperature range. Also I'm interested
> about good or bad experience using these components.

We have used both crystals and oscillators within the automotive
temperature range.  Some problems can occur with oscillators above the
125deg point - pick your manufacturer with care.

Crystals are a different story - some manufacturers will tell you that
there is no such thing as a high temperature crystal since it is a
"mechanical" device (i.e.: pick one and use it at whatever temperature
you require).  This is true to a degree, but there are other factors
which contribute to reliability at high temperatures (and, in our case,
chance of shock and vibration): package sealing, internal bonding etc.

Resonators: I've never found any spec'd higher that 85deg (someone out
there: I'd love to be proved wrong).  They have storage temps of 125,
but I believe that you would have severe problems running them that
high.
>
> I've already searched for these components and just found one crystal
> family which is offered for the automotive temperature range.
>
We've had good luck with Lap-Tech Inc.  Whatever they do in their QA
program they do it well.  The only product failures we've had that were
attributable to the crystal were due to *heavy* shock (indicated by
dents in solid stainless steel).  Also, we have never had start-up
problems with crsytals directly connected to the PIC at temps up to
150deg.  Look for Lap-Tech at;
  http://www.laptech.com/

If you're interested in high reliability oscillators, email me privately
(and tell me what your product is).  Be forewarned, though, high
reliability at high temperature doesn't come cheap!

--Matt

Matthew Bonner B.Eng. - Sunada Technology Corp. - Calgary, Alberta
mailto:mbonner@sunada.com