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TPS23753A: Transformer Reference Design PMP5270

Agustin Gonzalez
Prodigy 10 points
Part Number: TPS23753A

Hi, 

I have questions about the reference design PMP5270. 

1* In the bill of materials, proposes the Coilcraft HA4137-AL transformer, but it is discontinuous in Coilcraft. The alternative is Pulse PA1528NL, but also it is also discontinuous or Non-Stocked. I'm thinking of using A9967-AL. Should I make a modification?

2* C17, C20 and R18 have value DNP. should I place them? What values do they take?

thanks,

Agustin

  • 0
    TI__Expert 5615 points
    Agustin, I have received your question and am working to investigate the answer. I will reply again within the next 24 hours.

    Thank you for your interest in PoE products from Texas Instruments.
  • 0 in reply to Thomas Lewis
    TI__Expert 5615 points
    Agustin, After some consultation with our design services team, I can report the A9967-AL transformer will not work as an alternate source. It only has 500Vrms isolation, the bias winding is on the wrong side of the isolation barrier and the turns ratio/inductance are not correct.

    Either of the xfmrs listed in the BOM (HA-4137 or PA1528NL) should be available by contacting Coilcraft or Pulse.

    Regarding the other three components:
    * C17 should not be used.
    * It is good to have place holders for C20/R18 in case there are EMI challenges. Suggested values (if needed to be populated) are:
    * C20 in the 47-100pF range and,
    * R18 in the 75-100 ohms range.

    Please let me know if having additional questions.