TPS62148: Shorting 1.8V Vout to 3.3V case

Oba

Part Number: TPS62148

Hello,

My customer has an question for TPS62148.
They made their own board with TPS62148 and is testing abnormal case.
Now TPS62148 is set to output 1.8V. When shorting this 1.8V Vout to other 3.3V rail, they saw sparks and TPS62148 was damaged.
Does shorting 1.8V out to 3.3V rail usually damage the device?

Regards,
Oba

over 5 years ago

0 Jason Wang (BSR-MV) over 5 years ago

TI__Genius 9550 points

hi Oba,

Normally, single DC/DC converter doesn't support parallel structure (Vout), because has not Current sharing function.

if the device damaged, check if MODE pin pull high in your schematic(FCCM), if yes, pull MODE pin to low which can avoid damage happen.

0 Oba over 5 years ago in reply to Jason Wang (BSR-MV)

TI__Genius 17295 points

Hello Jason,

Thanks for your reply.
Why FCCM could cause the damage while PFM mode doesn't ?

Regards,
Oba

0 JohnTucker over 5 years ago in reply to Oba

TI__Guru**** 191445 points

Oba,

With FCCM, the inductor current can go very much negative when VFB is very much greater than the internal reference.

0 Oba over 5 years ago in reply to JohnTucker

TI__Genius 17295 points

Hello,

Thanks for your reply.
Sorry, I can't still understand.
Because TPS62148 has negative current limit function, I think so much negative current that could damage the device doesn't occur.

Regards,
Oba

0 JohnTucker over 5 years ago in reply to Oba

TI__Guru**** 191445 points

Oba,

It is likely there is some other failure mechanism. A detailed failure analysis would be required to determine the exact cause. The easy answer is to just not short the output to another voltage.

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TPS62148: Shorting 1.8V Vout to 3.3V case