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TPS2372: tps2372-4 schematic review

Tommy Tzeng
Genius 4805 points
Part Number: TPS2372

Hi Sir,

may i have your support to review TPS2372-4 schematic as attached? this is the application for 802.3bt. if have any problem or suggestion please kindly let me know,thanks for your great help.

PDTL-003 802.3bt PD circuit.pdf

  • 0
    TI__Mastermind 40120 points

    Hi Tommy,

    DT5 and DT6 should be bidirectional TVSs as a PSE can provide opposite polarities.

    I recommend considering a common mode choke in series with L4 and L6. Since this is a high power application, a choke will probably be needed.

    R26 seems low. It should probably be 50k.

    Lastly, I highly recommend using the PG signal to help delay the load when the PSE provides power to the PD (unless you already have a delayed load). This will help with interoperability where the PSE doesn't hit it's inrush current limit spec. 

  • 0 in reply to Darwin Fernandez
    Genius 4805 points

    Hi Darwin,

    thanks for your great support,

    as for the delay load, PG pin must be connected to the converter SS pin? may i connect to enable pin?

  • 0 in reply to Tommy Tzeng
    TI__Mastermind 40120 points

    Hi Tommy,

    Yes you can connect to an enable pin of a DCDC as well to delay the load. Thanks!

  • 0 in reply to Darwin Fernandez
    Genius 4805 points

    Hi Darwin,

    sorry~i have another question,

    in addition to the SS pin method, if there is no DCDC, the output is +48v directly,

    are there other circuit that can do delay load? do you have any related information or idea to share on hand? thanks.

  • 0 in reply to Tommy Tzeng
    TI__Mastermind 40120 points

    Hi Tommy,

    Usually, the load is controlled by a microcontroller. So the microcontroller will keep the load in a low power state until after 80ms.

    However, in some cases this must be done through hardware in which you can use an SVS (with a delay capacitor) sensing the PG pin to create a delay. Then you can you use this delayed signal to drive the enable pin of a load switch or a high voltage hotswap that connects to the load.

    Regards,

    Darwin