During production of a product based on ATmega1280 we had a few units (35 pcs out of 200 pcs) that failed testing. After some analysis it was found that the watchdog had restarted the unit during test. It seems like the watchdog oscillator is considerable faster in these 35 pcs.
- What are the tolerances I could expect from the watchdog oscillator?
Alternative theory: The moment the watchdog restarts the unit a lot of relays are being switched.
- Could it be a voltage spike that causes the watchdog to trigger?
Any input welcome!