Chip operating temperatures

[Mike Fahrion]

> > From:          "Mike Fahrion" <mfahrion at bb-elec.com>
> 
> > To take it one step further, it isn't terribly difficult to add a 
> > heater circuit that will turn on power to a several watt resistor 
> > when the ambient is below a certain threshold temp.  Almost always, 
> 
> Woah! I think we're getting a bit far afield here. Heat is the real 
> killer of electronics. I doubt that even -40C would be detrimental to 
> most electronics, especially IC's. 
> 

Sorry if I didn't explain myself clearly enough.  This method is used 
to extend the cold temp range of standard commercial parts (0 
degrees C - which can be a real problem).  The original post refered 
to problems getting industrial spec'ed parts for the application.  
The heater circuit turns on power to a heating resistor (usually just 
a few watts) below a threshold temp (say 0 degrees C).  Obviously it 
doesn't stay on indefinately - usually a bit of hysteresis is called 
for - say shut off the power at 5 degrees C.

If the cost &/or availability of industrial or mil spec parts is a 
problem this is a great solution.  One case where I used this 
solution was a design for use in Canada in an outdoor, unheated box.  
Several hundred of them have been working great with commercial spec 
parts for 3 years now.  In that case delivery of a required part was 
44 weeks vs stock for commercial spec, and 8 times the cost.  That's 
not too uncommon....

-mike
mfahrion at bb-elec.com