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TPS23861: Power 802.3at type 1(af) ports

Michael Balourdas
Expert 5455 points
Part Number: TPS23861

Hello,

Can you help me determine how I would configure the TPS23861 so that it would be only able to power 802.3at type 1(af) ports (eg 15.4W max out) rather than at type 2/1? It seems to me the device implies it can do this, but I am struggling to see which registers actually configure it for this.

 

Is it as simple as changing the TECLENn bits after startup to 0b00 so that the device can otherwise still operate in Auto mode?

Thanks,

Michael

  • 0
    TI__Mastermind 41780 points

    Hi Michael,

    The TPS23861 in automode behaves like a Type 2 PSE. In automode, it will only power up to Type 1 power if a Class 3 or lower PD is connected to it. If your customer has control on what is connected to the PSE on the PD design. For example, it will always connect to a Class 3 PD, then using automode is okay.

    However, if it is possible to connect to a Class 4 or higher PD, the PSE in automode will try to power it up to 30W.

    To only power Type 1 power, from a flow chart prospective:

    1. the TPS23861 can be in semi-auto mode.
    2. Then read detection and class is valid. (Class 3 or lower)
    3. set ICUT to 374mA
    4. power on port