does analog input need protection?

[MMoha.71]

I design a stm32h743 board without conformal coating

, it works good, when I shacked board, stm32h743 failed and burnt.

what's that reason?

thank you

[Uwe Bonnes]

Voltages and current with value near and above absolute maximum rating will kill the device.

[LCE]

Independent of coating, every IO of an active component / controller / SoC / whatever should be protected, unless it has some built-in protection (usually only specialized IO drivers), OR the connected circuitry - e.g. a voltage and current limited driver, or an open collector circuit - assures that the maximum ratings cannot be reached.

Protection can be as simple as a small value series resistor, or TVS diodes, ...

I would also recommend to never directly connect a controller pin to the outside world, except for only internally accessible programming / debug pins. Use drivers / receivers, plus protection circuits (and also think about where the surplus energy goes).