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TPS25940-Q1: behaviour of eFUSE during GND disconnection

Bart
Expert 6460 points
Part Number: TPS25940-Q1

We have a question regarding TPS25940-Q1 eFUSE latching version.

We have a normal slow-blow fuse between the eFUSE GND and global GND to disable the eFUSE in case of any internal short.

However, we are experiencing an issue - when the fuse fails and the eFUSE GND and global GND become disconnected, the output of the eFUSE remains active.

The fault pin is pulled low to the local eFUSE GND, and because it is an open-drain output, its MOSFET is enabled, allowing internal logic to continue working and keeping the output enabled.

Do you have advise what may be causing this issue, or any suggestions for testing?

  • 0
    TI__Guru** 105311 points

    Hi Bart,

    Thanks for reaching out 

    Can you please share some more details of EE and application use case.

    Even though eFuse ground is disconnected, there are internal parasitics which forms path from IN to OUT when device ground gets disconnected

    Are you trying to avoid series fuse in the main power path ?

    Best regards 

    Rakesh

  • 0 in reply to Rakesh
    TI__Guru** 105311 points

    Hi Bart,

    Can you help getting response for the above questions.

    Thanks

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 20 points

    Hi Rakesh,

    Sorry for the late reply, I hadn't noticed that Bart posted here about my problem.

    I'm sharing our schematic of the eFUSE configuration. As you can see if the F6100 blows the GND path is disconnected but the eFUSE is still operational and is letting the current pass through. The voltage between TP6102 and TP6103 is around +5V.

  • 0 in reply to Marin Stevic
    TI__Guru** 105311 points

    thanks for the details Marin.

    Can you test by adding parallel shunt resistor 1k~2k Ohm. When the fuse blows, this resistor provides reference path for the eFuse ground

    Best Regards,

    Rakesh