TMS320F280049C: MCU fail. Vdd shorted to Vss

sstefano78

Part Number: TMS320F280049C

Hi all,

I'm working on a "powertrain" project (+48V battery supply). Six months ago, I had developed my custom board with F280049 MCU.

In this months of tests I had 2 times same failure. Yesterday last occourence. 3V3 power supply goes to GND and MCU become hotter without particular reason. No other components are broken.

After removing MCU I can see that VDDs pins are shorted to VSSs. If I replace MCU and reflash it, all the system restart to work without other issue.

I attach my schematic. Have I made connection errors? What can be the causes of a similar failure?

Best regards,

over 5 years ago

0 Peter Galicki over 5 years ago

TI__Expert 8105 points

Stefano,

I check you power pin assignments - they look good. One possibility is that maybe one or more decoupling caps have been populated with a resistor. I understand that when you probe the failed MCU the VSS is shorted to VDD. Did you test the VSS and VDD on the board without the MCU?

Regards,
Peter

0 Peter Galicki over 5 years ago in reply to Peter Galicki

TI__Expert 8105 points

Stefano,

Also from your schematic it is not clear if the VDD pins are interconnected on a single net (such as a power plane) - if not, they should be.

Regards,

PEter

0 sstefano78 over 5 years ago in reply to Peter Galicki

Intellectual 365 points

Hi,

yes I tested VSS and VDD without MCU and they looks good.

When MCU fail 3v3 regulator goes to current limit state. If I remove MCU, all seems to be ok.

0 sstefano78 over 5 years ago in reply to Peter Galicki

Intellectual 365 points

Yes, VDD come from single net after L80 ferrite.

Now my question is: What can cause the (only) MCU to break?

Best regards,

0 Peter Galicki over 5 years ago in reply to sstefano78

TI__Expert 8105 points

Stefano,

Some of the things that can cause the MCU to fail include providing voltage to power pins that is outside of spec and mishandling the chip/board where an electrostatic discharge can damage the device.

Regards,

Peter

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TMS320F280049C: MCU fail. Vdd shorted to Vss