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TPS23861: POE LED control

Ufuk Karaaslan
Prodigy 120 points
Part Number: TPS23861

The TPS23861EVM-612 uses VPWR and a 22V zener to drive the POE LED. That consumes a lot of power. Can I use the Gate signal and drive  the LED using VDD power as in the attached schematic? What threshold would you recommend for the gate voltage to turn on the LED?

POE_LED_DRIVE.pdf

  • 0
    TI__Mastermind 41770 points

    Hi Ufuk,

    This is mainly just for the EVM evaluation to see if the port was ON. I do not recommend using the GATE of the PSE since the extra load and gate capacitance could cause GATE drive to be unstable.

    In real application, a lot of times I see the microcontroller on the PSE system drive the port LED in synch with the data transfer. Or when the microcontroller gives a port power ON command to the PSE, it can connect a GPIO to tell a switch to turn ON the LED. Then these can be biased with a 3.3V rail like you have on your attachment. Please let me know if this helps. Thanks!