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TPS23754: The way for recognizing POE or adapter input

Shinichi Inoue
Guru 19701 points
Part Number: TPS23754

Dear Specialists,

My customer is considering TPS23754 and has a question.

I would be grateful if you could advise.

---

I have one question regarding TPS23754.

It is necessary to have a specification that informs the internal software whether the external power supply or PoE + is supplied by TP23754.

So I wondered if the T2P terminal could be used, but the enable conditions for T2P are as follows.

(VAPD> 1.5 V) OR (1.55 V< VPPD< 8.3 V) OR (type 2 hardware classification observed)

When supplying power by either external power supply or PoE +
Either way, T2P will be active.

Is it possible to output some kind of detection signal only when the TPS23754 is supplied with external power?

Or is it necessary to add a detection circuit externally?

---

I appreciate your great help in advance.

Best regards,

Shinichi

  • 0
    TI__Mastermind 21320 points

    Hello,

    T2P is intended to signal if 25W of power is available (assuming the adapter is 25W). So T2P differentiates between Type 1 and Type 2 power, not the power source (adapter or PSE). 

    I think the easiest way to do this would be to build logic with the APD pin. If adapter is present, APD>1.5V and this signal could be used with an optocoupler to send across isolation barrier. 

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

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    Guru 19701 points

    Hi Michael,

    Thank you for your reply.

    I understand APD pin should be used for detecting adapter input.

    I'll share this information with the customer.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi