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STM32F1 and STM32F4 external oscillator circuit shorted

Question asked by pavelm on Feb 11, 2016
Latest reply on Feb 12, 2016 by pavelm

I am facing quite strange issue when some of my boards are suffering very rarely from burned path in the MCU for external oscillator input.

It happen with STM32F1 and also STM32F4 in the way, that I can measure less resistance in OSC_IN than in good MCUs.

Nothing else than this pin is wrong.

So this issue is happening from nothing. For example it works for 50 times and then next time the problem occur irreversible. There are even occasions when the problem is fixed on its own, but definitively the problem is just in the processor - after MCU replacement all is working again and the issue will not occur anymore.

Is there any possible explanation for this?

When the issue occur, MCU is still working, but only from internal oscillator.
All boards are identical, but the issue happen only to maybe 1% from thousands.

Thank you