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What are the situations which would cause an MCU to not turn ON?

Question asked by Yonathan Foto on Jan 17, 2019
Latest reply on Jan 18, 2019 by Yonathan Foto



My company has been using an MC9S08QG8 MCU in one of our products for years and most recently during production, it was found that maybe 1/100 times when resetting AC Power, there would be no response from the MCU. But even once that happens once you reset the AC power the unit will continue to work normally.


One of the initial steps in the program during variable initialization is to set the PWR LED ON but the manufactures has informed us that the LED is not ON during this situation which means the MCU is Off and did not start.


The Manufacturers also informed and showed us graphically VDD is stable and 3.3V.


I have also informed them to check if the Reset Pin on the MCU is Held in a reset state (GND <~1.5V) and it is not.


We have also confirmed that the MCU is real and not a fake clone since we are getting it from a reliable distributor.


If anyone has experienced a similar problem any advice will be useful.


Thanks in advance!