Hi All,
I have a small Rabbit CPU based board, it's rated max temp. to 50C, but in the field it can easily go up to 60C in the cabinet it's stored in. What can actually happen to the board when operating above it's rated temp. (e.g. RAM errors etc.)
Thanks, Sean
Anything. Literally.
For all anybody but the makers of that board and the parts know about it, it could explode, melt or just keep on working just fine except if used on by your boss, on a Thursday, May 12th, when it'll exhibit exactly the one bug you bet your job on having solved for good.
Or maybe it'll do none of the above and actually behave in a completely unexpected way.
Most likely it'll experience some sort of soft error, most likely due to some circuit not keeping up with the clock (CMOS logic slows down with increasing temperature), or timing skew (because some of the logic will slow down differently than other parts), or an oscillator refusing to work. You _may_ experience problems with EEPROM that's written to during that time.
99 out of 100 will probably work fine, but the 1 out of 100 that misbehaves will give you no end of grief.-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
That depends. A 10'C temperature impact will effect mainly the product lifetime - All components get less reliable as the temperature increases. eg You can get 85'C caps, and 105'C caps, and in an elevated temp design, you should use the 105'C ones. Likewise the RAM and CPU have rated max die teperatures, and that heat has to get all the way from the die, to ambient. It is possible that a 60'C ambient, mostly Idle cPU can have a cooler die, than a 50'C ambient, full speed CPU. A heatsink glued on can reduce the die-ambient thermal resistance, and so allow a faster operation/higher ambient
-jg
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