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TPS2553-1: FAULT Signal

TI-CSC
Genius 10560 points
Part Number: TPS2553-1

Tool/software:

Hello E2E Experts,

Good day.

I chose the latch-off model.
But when a short circuit occurs, the fault output switches from high to low and then back to high (and does not stay low all the time), even if a short circuit occurs..

Attached the diagram.

I tried removing the connection FAULT pin and EN pin, and to my surprise, the protection against short circuit or overcurrent is working correctly.

Can you help explain why or how this phenomenon happens?

Thank you in advance.

Regards,

TI-CSC

  • 0
    TI__Expert 5015 points

    Hi TI-CSC,

    My interpretation is the following:

    1. VIN, EN high
    2. Short circuit applied
    3. FAULT asserts after 7.5 ms (current limit deglitch time).  Consequently, EN is disabled
    4. With EN low, current limit block no longer reports fault signal.
    5. FAULT de-asserts after 7.5ms.  Consequently, EN is enabled.
    6. Repeat/return to step 3

    This is effectively the auto-retry circuit shown in section 10.2.2 of the datasheet.

    This also conforms to the behavior described in section 10.1.1. "The latch-off devices remain off and do not resume normal operation until the surrounding system either toggles the enable or cycles power to the device."

    When you remove the FAULT/EN short, the device is not receiving the EN toggle required to restart normal operation, so it stays latched off.

    Regards,
    Eric