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TPS2549: output safety design question

Matt Wang
Prodigy 70 points

Part Number: TPS2549

Hi team

I would like to ask about the USB port safety design of TPS2549. Should I put the polyswitch at TPS2549 output pin to meet safety requirement?

We didn't find the safty description in spec.

Thanks

  • 0
    TI__Mastermind 30000 points

    Hey Matt,

    Thanks for posting your question on E2E. So there is actually no need for a polyswitch as the TPS2549 has over current protection, as it is able to shut off the output voltage based on the current threshold. I attached the Functional Block Diagram for the TPS2549, and numbered different sections to help run through how this part is able turn off VOUT based on a over current.

    1. The TPS2549 has an internal current sense which is tied to the current limits, whose values are determined based on the resistors tied to ILIM_LO and ILIM_HI

    2. The current limit is tied to a driver, which is connected to a FET as well as an OR gate

    3. If there is a case of OC, the gate on this FET opens, cutting off the voltage to the OUT pin.

    4. The gate on this FET will then be closed, allowing for the excess voltage to drain

    5. This FET is then closed signaling that there has been a fault.

    If there is a MCU within this design, you can connect the fault pin to a GPIO, so that your systems knows when a fault has occurred.

    I think this answers your question. If so, please click on This resolved my issue to close this thread

  • 0
    Prodigy 70 points

    Thanks for you reply.