We've been building a PCB with four STM32F091s on each PCB and we've built about 50 units by now (over about 3 years). I have now seen three PCBs where the ADC readings are 'bad' on two of the four micros. By 'bad' I mean conversion values are 30% ish low.
With the design having been stable for quite a while, the chances of uncovering a new bug seem slim, but chip damage seems even more unlikely. The fault also 'went away' on one of the PCBs, so more evidence that it's not damage.
The ADC reference is VDD 3.3V on all the chips, and they all run the same code.
Anyone got any thoughts?
