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TPS23753A: Suggest Design for Isolated +/-15V POE PD

Benjamin Bawkon
Expert 1065 points
Part Number: TPS23753A
Other Parts Discussed in Thread: PMP9175, TPS23755EVM-894

Hello,

I have used a variation of PMP9175 for a previous project with great success.  I now have a requirement for a POE PD circuit which can provide an isolated +/-15V output.  I could work with anything between +/-12 and +/-24, but +/-15 is ideal.  Very little power is required - Likely less than 3W.

Does TI have any reference designs for something like this?  I've tried the reference design search, but didn't have any luck.

Obviously, I could create my own circuit based on PMP9175, but I'd rather start with something closer to my requirement if it's available.

Thank You,
Ben

  • 0
    TI__Expert 5615 points

    Ben,

    Thank you for your question.  As it is the weekend, our answer will come later than usual.

    I am assigning this question to our PME, who will reply by Monday COB...worse case.

    Thanks for your understanding,

  • 0 in reply to Thomas Lewis
    TI__Expert 3700 points

    Hi Ben,

    Thank you for your question.

    For a +/-12V output design, I recommend referencing the TPS23755EVM-894.

    If you take a look at the schematic on the TPS23755EVM-894, you will notice the transformer has two windings in parallel on the secondary side of the transformer (pins 7/10 and pins 8/9) as shown below:

     

    I recommend leaving pins 8 and 9 as they are in the EVM and these will be used to create your positive 12V rail.

    I also recommend taking pin 10 and connecting this to a diode then ground (cathode to ground and anode to the transformer). Pin 7 will be used to create your negative 12V rail. An output cap will also need to be added between the negative rail and ground. You can most likely just grab C10 and use this as the output cap for the -12V rail.

    Please let me know if this does not answer your question and/or if you have any further questions. Thank you!

    Best Regards,

    Brett Colteaux

    PoE Product Marketing Engineer

  • 0 in reply to Brett Colteaux
    Expert 1065 points

    Brett,

    That looks to be a great starting point (perhaps with exception to availability of that transformer).  Thank you.

    Best Regards,
    Ben

  • 0 in reply to Benjamin Bawkon
    TI__Expert 3700 points

    Hi Ben, 

    The transformer used in this design is dual sourced and you can use either Linkcom or Wurth Electronics to obtain the transformer.

    If you are having any trouble with obtaining the transformer used in this design, I can help to share our transformer contact information via private message so that you can obtain this transformer.

    I will send you a friend request on E2E momentarily. Please accept and I will be glad to provide this information to you privately. Thank you!

    Best Regards,

    Brett Colteaux

    PoE Product Marketing Engineer