Chip operating temperatures

[Stephen Dubovsky]

At 12:15 PM 9/24/96 EDT, you wrote:

>But what about temperatures below zero degrees? Here in the mid-atlantic
>area of the U.S., there are plenty of mornings where I have to scrape
>off the frost from the windshield, or replace the radiator because
>I forgot to add anti-freeze. Will the chips works in the cold region
>properly?
>
>- Bruce


  I am an EE w/ a few years experiance so I HOPE I know what Im talking
about...  Most chips will work outside their temp range, but how well is
another story.  Most analog parts simply wont meet published specs (but when
do they?) like offset, slew rate, etc.  Most digital stuff still works, but
the timing parameters must be relaxed.  Every now and then you can find a
part that wont work in the cold, but often it can be replaced (w/ another
identical part).  Often the automative and comercial temp ranges are the
same part, but one is tested and guaranteed to the more extreme temps.  The
only real difference I can tell (from practical experience) is the
packaging.  The Mil spec stuff is almost always ceramic which may take the
temp cycling better, but the comercial and auto stuff appear to be in the
same plastic package (hope it doesn't crack at low temp).  
  In a nutshell:  If you derate the comercial parts they often work well
outside their spec temp range.  
SMD  

Remember that your interior can get VERY hot (when your away w/ the windows
rolled up) so dont assume your EFI computer will never have to work at 140F+
ambient if its in the passenger compartment (still want to be able to start
your car, right? ;)

  Oh, and the way to keep from replacing the radiator because you forgot to
add antifreeze is to use an air cooled engine;)  (Im a 911 owner)