• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 139 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS23758: Substitute / redesign suggestions needed: part not available. 10W PoE

Klaus Renner
Prodigy 20 points
Part Number: TPS23758
Other Parts Discussed in Thread: TPS23750, TL431, , TPS23730, TPS23731, TPS23734, TPS23753A, TPS23755

I have this part designed in, it's working properly, we've built 20 boards with it, but it is now not available.

I need 25 pieces in the next month for product validation. This would carry me through the end of the year, but I'm not having luck even getting a few samples. Very frustrating.

So I need to very quickly redesign using a more available IC.

I've looked at the TPS23750, '730, '734 and they all should be able to do the job, but none of the suggested circuits or EVM topology meet my need.

I only need to supply 10Watts. I already have a transformer and would like to keep using it. The TPS23758 design uses Flyback topology and Primary Side Regulation. My regulation needs aren't super stringent. I want to keep the Flyback topology. PSR would be nice but I can add a TL431 and optocoupler if needed. According to the datasheets, all the parts I've been looking at can to Flyback and PSR.

The biggest problem is that this redesign must work the first time and none of the eval / suggested circuits I see are close enough to give me confidence they will work first time.

The 23758 worked perfectly the first time. I'm not new to SMPS design / layout, so this is not a big jump for me, but I want to have a conversation with someone who really knows these parts before I commit. Also if there are other ICs I should consider, I'm game.

Thanks

  • 0
    TI__Mastermind 21320 points

    Hello, 

    Just as a note, all IC's from all vendors will probably face a shortage. This is not unique to the TPS23758. 

    As you pointed out the TPS23730, TPS23734, and the TPS23731 support PSR. All of these devices are rated for higher power, so their EVM's reflect that. The TPS23731 is similar to the TPS23758 in that they are both synchronous PSR flybacks for 5Vout. 

    The other 13W IC I could recommend is the TPS23753A. It does not support PSR, but there are some 5V designs in the TI Reference design library. 

    The other important thing to know is that the TPS23758 integrates the primary switching MOSFET of the flyback. Only the TPS23755 does this as well, all other IC's this FET is external. That will be a layout and sourcing/BOM change to consider. 

    I think to keep your transformer, which is probably made for PSR, the best IC to fit your design needs is the TPS23731. You can keep dithering, advanced startup, and PSR. Technically a PSR transformer could work with an optocoupler feedback, but I guess its like paying for something extra that you're not going to use. 

    Let me know if you have any other questions on this!

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

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments