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TPS23861: how to connect TPS23861 and TPS23751 with and POE input

Bonnie Chen
Intellectual 1150 points
Part Number: TPS23861
Other Parts Discussed in Thread: TPS23751, TPS2373, TPS23880

Hi Team,

can you take and example circuit for below condition?

this is an AP router device, only one input with POE(example 60w)

need one TPS23751 as PD to supply AP router system and had one PSE TPS23861 as AP router output to external.

thanks a lot!

  • 0
    TI__Mastermind 41770 points
    Hi Bonnie,

    Note that a 60W design using Type 2 (~30W) ICs will be considered non-standard applications. Rather, we would recommend using the new IEEE802.3BT-ready devices like the TPS2373 and the TPS23880.

    However, I understand that some designers have control over both sides of the cable and so interoperability with other standard PDs is not a hard requirement. I recommend looking at the below link to a training video that discusses the methods to achieving high power with our AT portfolio of ICs (like the TPS23751 and TPS23861).
    training.ti.com/high-power-poe-design-considerations

    But for a quick answer, you can use the TPS23751 in 60W if you use a current booster circuit between RTN and VSS. We do a similar solution in the PMP5881 schematic from the below link.
    e2e.ti.com/.../102863

    On the PSE side, you can configure the TPS23861 for higher power by using two 30W channels on each pair set of the Ethernet cable. For example, the EVM has two RJ45s that is configured in this fashion. You can use a microcontroller to turn on both channels to provide 2x30W to the PD. This is also discussed in the high power training video about in detail and how to use the TPS23861EVM GUI to test this 60W solution out on bench.

    Regards,
    Darwin
  • 0 in reply to Darwin Fernandez
    Prodigy 20 points
    Dear Darwin,
    sorry for confusing .
    what we asking is the AccessPoint (with a 25watt PD) should capable to support a single PSE output (on LAN port) to extend next PD device.
    My question is how to connect the extend PSE chip to the PSE(WAN port) power?
  • 0 in reply to Darwin Fernandez
    TI__Intellectual 1150 points

    Hi Darwin,

    I check your reply but looks not indicate correct for my questions.

    my questions is my AP router with POE input and PSE output, how my PD schematic and PSE circuit combine together.

    any reference design circuit or recommend?

  • 0 in reply to Bonnie Chen
    TI__Mastermind 41770 points
    Hi Bonnie and John,

    Sorry I had misread your initial post. For PoE pass-through system, it is recommended to connect the TPS23861 design to the VDD-RTN of the PoE PD. Note however, since you have a PoE PD requesting 25W, you will not have the 30W for the pass-through PSE if it is a supposed to be a Type 2 PSE.
  • 0 in reply to Darwin Fernandez
    Prodigy 20 points

    Got it and Thanks

    John