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Old 08-25-2009, 12:12 PM   #2206 (permalink)
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Originally Posted by montgoss View Post
This was a long time ago, but I finally got through the whole thread and don't think this has been fully addressed...

Is it just the atmega8 that has issues with locking up the processor if the voltage goes below 0v or above 5v? Or is it all the Atmel chips? Something that causes a lockup such that the watchdog doesn't even trip concerns me ...
I think this sounds like generic CMOS latchup - it affects many VLSI circuits. Sometimes the solution is as simple as looping the wires through a ferrite ring on their way from controller to PCB (close to the PCB). By all means protect the inputs with small caps to ground, and reverse biassed diodes to the power rails as well.
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