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TPS23753A: POE supply with 24V output

Steve Fister
Prodigy 70 points
Part Number: TPS23753A

We are using the TPS23573A with the POE13P-24L and a simple rectifier for 24VDC output.  The power supply input current draw starts to increase above 45Vin with consequent heating of the output rectifier diode.  Do you have loop compensation values tested for 24V with this output configuration?

  • 0
    TI__Genius 9230 points
    Hi Steve,

    From what I have tried looking for, we do not have that specific configuration (13W, 24V out, Isolated, Diode rectified, TPS23753A) tested. I can check with a team mate and see if we can give you some help.

    If you don't mind, could you post your schematic? You can also send it to me privately.

    Thanks,
    Thomas A.
  • 0 in reply to Thomas Amlee
    TI__Genius 9230 points

    Hi Steve,

    I don't have any comments on the schematic. As for the primary side FET heating up, I would be sure that your FET has a low enough gate capacitance & your slew rate is a fast enough to keep power consumption down. In the app note mentioned below, we use a smaller (1.4A to your 4.1A), but quicker FET (smaller gate charge, faster turn on/off times): FDC2512 (www.onsemi.com/.../FDC2512-D.pdf) while using a smaller gate resistor.

    We don't have any 13W, 24V ouput PoE designs, but the most I can do is point you towards this app note: www.ti.com/.../slva305c.pdf

    It's a comprehensive guide for designing a flyback with the TPS23753A.

    Thanks,
    Thomas A.