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Original question:

[FAQ] TPS2373: What is the functionality of the TPH, TPL, and /BT pins for TIs IEEE802.3bt-ready PoE PDs?

TPS2373: TPS2373

James Nahra
Prodigy 10 points
Part Number: TPS2373

how is the PSE class 7 and 8 distinguished when the TH, TL, and BT logic is the same (000) ? 

thank you

Jim 

  • 0
    TI__Genius 14645 points

    Hi Jim,

    The intention of the truth table for the state of  TPH,TPL, and BT is to distinguish between PSE Types. Therefore there is no way using TPH,TPL, and BT to determine Class 7 vs Class 8.

    BT refers to IEEE802.3bt standard compliant, therefore when this pin is high the PSE is at/af standard compliance and bt compliant when logic low. 

    IEEE802.3bt standard allows for Class 0-8, therefore using the two additional states it would be impossible to make a combination between TPH and TPL to support differentiation of class types. Therefore the states only differentiate between types and groups of classes such as 0-3,4,5-6, and 7-8.

    Very Respectfully,

    Brandon Beader