Microcontroller pin may stick high or low

[eem2am]

We are doing low power SMPS’s with microcontrollers supplying the PWM to the FETs.

Switching frequency = 100KHz.

The problem is that micrcontrollers often experience a “stuck pin”, where a PWM pin sticks low or high.

Obviously the watchdog will catch this, but if a pin gets “stuck high”, then the FET will be stuck ON and we will experience an overcurrent which will blow up the FET before the watchdog can respond.

Do you have any stock circuits that can detect a “stuck high” PWM pin and pull it low?

 

[Tahmid]

Hi,
One way to stop this is, before you turn off the timer, set duty cycle to 0 and then wait for the timer to overflow a few times and then turn off the timer. This is how I overcame my problem when I used ATMEGA for PWM.

Since your duty cycle would be 0, the pin would automatically become low.

Hope this helps.
Tahmid.