TPS2492: TPS2492 Back to Back FET failing

Michael Reilly

Part Number: TPS2492

Tool/software:

Hello,

I am trying to use the TPS2492 with a back to back FET design. I am using the UVEN to turn off the FETs in an E-Stop condition. I am having the first FET on the battery side failing short when the Enable signal is pulled low under power (~5A load).

I have tried adding TVS protection and a capacitor similar to the output but that didn't work.

Do you have any suggestions on what the cause of the problem could be? I can take measurements of different things if that helps as well.

over 1 year ago

0 Michael Reilly over 1 year ago

Prodigy 236 points

Just want to update with what I tried today.

I changed the circuit so that the E-Stop/Enable signal causes an OV error rather than pulling down the UVEN signal. I did this so that the pull down on the FETs was 125mA and not 2mA, this reduced the fall time to 5uS. Unfortunately that still did not solve the problem.

The problem seems to be that after disabling from E-Stop by applying 3.3V to the OV pin that upon re-enabling (brining OV to 0V) while under a load the MOSFET fails.

0 Amrit Jit over 1 year ago in reply to Michael Reilly

TI__Mastermind 31501 points

Hello Michael,

Thank you for reaching out to E2E.

Do you have any waveform? wanted to check what's causing the MOSFET to get failed.

Have checked the design calculator and check SOA limit of MOSFET.

I have attached the design calculator below.

https://dr-download.ti.com/design-tools-simulation/calculation-tool/MD-CXmOeWd49v/01.00.00.0J/slvc033j.zip

Thanks

Amrit

0 Michael Reilly over 1 year ago in reply to Amrit Jit

Prodigy 236 points

Hi Amrit.

Thanks for getting back to me. I root caused the issue and it is the SOA the 22uA of source current doesn't turn on the FETs on fast enough.

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TPS2492: TPS2492 Back to Back FET failing