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TPS23750: 24V AUX power to TPS23750

Part Number: TPS23750


As per slvs590b.pdf document, the TPS23750 is designed to operate from 24V adapters when we use Auxiliary Power ORing option-2.

Can you please confirm, will the circuit below (reference:TPS23750EVM-107) work if I connect 24V to the marked point? Do I need to add more components(capacitors) to make it work?

Thank you.

  • Hi Yash,
    You will want to add a series diode to the +24V input. If you don't, the 48V of the PoE will try to over-drive the auxilary 24V input. You also need to tie the "GND" of the 24V input to RTN to be consistent with option 2. Please note that the drawing above is showing it tied to VSS.
  • Hi Artem,

    Thank you for your quick answer.

    In my application, the device is powered either via PoE or via AUX power supply.

    Can the device be powered by PoE when the GND of the 24V input is connected to RTN? or Do I need to disconnect the GND of the 24V input with RTN when using PoE?

    Thank you in advance

  • Hi Yash,

    You don't need to disconnect the GND of the 24V input.  During detection and classification the RTN to VSS internal FET is disconnected so the 24V Aux doesn't interfere with the PoE handshake. Once the PoE goes up to 48V it will supply the power, b/c 48V > 24V.  As I mentioned in my previous post you do need to add a series diode for the 24V input.