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STM32F042 blown up - what could be the reason?

Question asked by muddvl on Apr 12, 2016
Latest reply on May 4, 2016 by muddvl
Hi there, we are prototyping a product that involves an STM32F042. It was working great but ... two units got the STM32 blown up! It just gets really hot and nearly pulls the VDD down.

Some details and ideas:

- We didnt accomplish the power ferrite / caps requirements, so only 2 caps were in the design, and no ferrite between VDD and VDDA was present. Now we've changed this, but could this cause the issue?

-There is a 3V3 CAN transceiver in the design too. Can this guy fry the STM32 for some reason? Overvoltage on the can lines? Voltage when VDDA was not ready on the STM32...?

-There is a USB device attached to the system. Only USB ground goes into. Could some overvoltage come from here and fry this? However, the DC/DC stage didnt suffer any damage...

-BOOT pin was pulled down to GND without pull-down resistor (changed now). Could this cause the problem?

Also, the units were hand soldered. This is for sure a source of issues, maybe there was some pin dodgy on the design ....

We have made all these changes on the design, however, any help/suggestion here is more than welcome.

Thanks so much.

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