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TPS2373: TPH, TPL, BT/ pins & 30W PSE Detection

Felix Arul Rajesh Francis
Intellectual 470 points
Part Number: TPS2373

Hi 

We have implemented the TPH, TPL, BT/ pins and interfaced with MCU to detect the state.

How can we differentiate between 15W PSE & 30W PSE in this implementation?

We are able to get 60W detection and 90W detection, but 15W & 30W is not happening.

For 30W PSE detection, 2-event is mandatory to identify this (or) initial 15W powering and later getting another 15W through LLDP is still possible?

In our implementation, we are not able to source the power from the 30W PSE connected with the Uplink PD, where TPS2373-4 PD exists.

Regards,

Felix.

  • 0
    TI__Mastermind 21320 points

    Hello Felix, 

    The TPH, TPL and BT indicator statuses are discussed in table 2 in the datasheet. 

    For a Type 1 (15W) PSE:
    TPH: HIGH

    TPL: HIGH

    For a Type 2 (30W) PSE: 

    TPH: HIGH

    TPL: LOW

    If you are negotiating power through LLDP, you cannot negotiate higher than the physical hardware negotiation (according to PoE standard). So if the class resistor gives you only 15W, then the PSE can only give you 15W, LLDP would be able to get you less. Some PSE's are not complaint and do allow you to negotiate more, but this is beyond my scope. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments