TMS320F28377D: All VSS need to be connected?

TETSUMI NARITA

Hello,

All of VSS BGA pads of TMS320F28377D need to be connected?

Recently I got failure case of TMS320F28377D chip (it burnt). And result of X-ray observation, there are some bad soldering on some of VSS pad. Could bad soldering joint on VSS pad cause chip failure?

over 5 years ago

0 Cody Watkins over 5 years ago

TI__Mastermind 42195 points

Narita-San,

We require that all VSS pins be externally connected. This will ensure that the device meets datasheet specifications.

Now if one or two of the VSS pins were not connected I do not expect this to destroy the device quickly. It could shorten the lifetime of the device, but will probably not destroy it in a few hours of testing.

My first guess is that the device would fail open in this case, but it depends on the failure mechanism and it is possible that the device could fail "shorted". If the device has a "short" fail then it would cause the device to get hot as you indicated.

It is difficult to say what caused the failure with just that information, but your hypothesis is not unreasonable.

Regards,
Cody

0 TETSUMI NARITA over 5 years ago in reply to Cody Watkins

Prodigy 40 points

Hi Cody,

Thank you very much for reply!

0 Cody Watkins over 5 years ago in reply to TETSUMI NARITA

TI__Mastermind 42195 points

Narita-San,

one more question, how many VSS pins were disconnected? If it were a significant number of pins unsoldered and the device was drawing a high amount of current this issue would be more likely.

Regards,
Cody

0 TETSUMI NARITA over 5 years ago in reply to Cody Watkins

Prodigy 40 points

It's not 100% sure, but according to X-ray observation, there are three suspected connection.

Which is R7, L11 and M11.

0 Cody Watkins over 5 years ago in reply to TETSUMI NARITA

TI__Mastermind 42195 points

OK, thank you for the information.

Depending on the current consumption of the device could lead to an overstressing of the VSS pins, but I cannot say for sure if this was the root cause of your failure.

Regards,
Cody

0 TETSUMI NARITA over 5 years ago in reply to Cody Watkins

Prodigy 40 points

Yeah, I understood that it's possible, but not conclusive...

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TMS320F28377D: All VSS need to be connected?