MCU Vcc to GND SHORT

Hi

I am using a STM32f0 family microcontroller

but its getting failed in different stages Reason for that is vcc to GND pins shorted. We are facing the issues in both at our supplier, in-house and customer end.
I thought this might be because of 3.3V supply regulator L78L33ABUTR. But there is no problem with the regulator.

Regards,
CMA

Hi,

Semiconductors fail because of:
* overvoltage
* overcurrent
* overtemperature

One of these may cause your device to fail.
* It's unlikly that you overheat a microcontroller in a way that it gets VCC and GND short. --> but check on overtemperature.
* I'd say it's unlikely that overcurrent will damage your microcontroller. --> but check on overcurrent
* overvoltage. Means voltage beyond specification, on any pin, even for a very short time, like nanoseconds. It could be positive or negative overvoltage.

Some possible sources of overvoltage:
* ESD. During manufacturing, storing, transport, assembling, or even on your board
* VCC overvoltage: Not properly decoupled voltage regulator, bad PCB layout, transients on power supply
* overvoltage on any pin: EMI, ESD, bad layout, (switching) inductive loads

There are standards to follow.
* use a solid GND plane on your board, without cuts, without other traces.
* use (multiple) vias and very short traces to connect the nodes to GND.
* place a power supply ceramics capacitor on every supply pin of every device with short traces to GND.
* place ESD protection on every signal that enters/leaves your PCB.

Most likely:
Bad PCB layout. --> show us your PCB layout.

Klaus

Presume you clarified that it's not a solder short.

The failure is most likely caused by a massive VDD overvoltage or by overloading a specific pin. In the latter case, you should be able to locate the respective pin with in-circuit test methods. Schematic review should also show the most likely candidates.

FvM said:

Presume you clarified that it's not a solder short.

The failure is most likely caused by a massive VDD overvoltage or by overloading a specific pin. In the latter case, you should be able to locate the respective pin with in-circuit test methods. Schematic review should also show the most likely candidates.

Click to expand...

MicroController failure - Vcc and GND short. I also checked the board for track short but no track short identified. After replacing with new mcu, its working fine.we observe this failure randomly.

Regards,
CMA

Hi,

as already mentioned in post #2:
The PCB layout could give useful informations.

Klaus

Is it possible you are inadvertently configuring an input pin as an output?

FWIW my experience: a time I has having strange STM32F failures when running from 3.3 volts, I completely solved by using BAT54S schottkys as clamps on the 5 volt compliant inputs.