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TPS23882B: PoE Controller implementation question

Jimmy Lai
Expert 6845 points
Part Number: TPS23882B
Other Parts Discussed in Thread: LM5017, TPS23882EVM-084, TPS23881, TPS23882

Dear Team,

 

Due to our protential customer are interesting the Marvell – IRONMAN projects, and would like to add the PoE functional into product spec to evaluate design.

 

After I reviewed the TI.TPS23882B (PoE controller) datasheet, then have one more question to asking for “VDD supply voltage” requirement as snapshot,  

Does this VDD rail have any power sequence must be follow-up? Becausse the datasheet is recommends to use LM5017 device to implement.

 

But, based on my design experience, I think TPS23882B is not exist any power sequence request and just confirm the power rail necessary up to 3.3V (and follow-up the range tolerance), then PoE controller can implementation successfully for 802.3at, right?

Many Thanks,

Jimmy

  • 0
    TI__Mastermind 25666 points

    Hi Jimmy,

    We recommend LM5017 series for the UVLO detection, you can refer to the TPS23882EVM-084 daughter card schematic for reference (UVLO is set to be ~32.5V):

    While there are no power on sequence for our PSE devices, it's generally recommended since a VDD UVLO fault can occurred. Is the wondering why we recommend LM5017 or do they want to reduce BOM cost? 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    TI__Expert 6845 points

    Hi Raymond,

    Understood, but I have one more question to asking for this VDD rail voltage design;

     

    If POE_CTRL TPS23881/ TPS23882 device are not have any power sequence requirement, could we use the CPU/ MAC sequence follow-up req. (as below example) P3V3 rail to replace the LM5017 device (for TI recommended)? e.g. attached file use TI.TPS568231RNNR device.

     

    If my idea can working, its can achieve BOM cost and save pcb placement goals together, therefore please help to confirm its, tks!

    Many Thanks,

    Jimmy