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TPS2375: Connection confirmation along with TI power rail for low power PoE-PD device

JOHANN van niekerk
Prodigy 30 points
Part Number: TPS2375

Hello

Im designing a PD device and have used the TPS2375 along with a 60-5v simple switcher, battery charger and 3v3 LDO. I have two questions 

1) On the TPS2375, all documentation shows that the incoming negative rail after the bridge rectifiers connects to VSS on the TPS2375 ONLY and no connection to system ground.. Does all return current flow through the TPS2375 device? 

2) I have a design requirement for 3v3 at 1Amp max, under normal load 500-600mah. does this setup look feasible? 

Just to clarify, the PoE transformer and terminations is not shown in the example. 

Working from Left to right to produce a battery backed-up 3v3 1 Amp rail.

  • 0
    TI__Mastermind 21320 points

    Hello ,

    1.) There is an internal MOSFET between VSS and RTN that is connected one detection, class and inrush are complete.

    2.) I can only speak to the PoE TPS2375 and the immediate DC_DC converter, which looks okay. However, I would recommend the TPS23753A or the TPS23758. 

    Please see our list of reference designs. I put a link filtering 3.3V output and 3A or less  output. There are multiple designs that should suit your needs. 

    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
    Prodigy 30 points

    Hi Michael 

    Thank you for the response, I am trying to get away from the cost and size of a isolated design, 

    Im looking for the smallest footprint design possible and none of these Transformers are small enough. 

  • 0 in reply to JOHANN van niekerk
    Prodigy 30 points

    Looking closer at the transformers used I found one that stands out and should work 750313109 WE 

  • 0 in reply to JOHANN van niekerk
    TI__Mastermind 21320 points

    Hello,

    Yes there are many different sizes for transformers. The lowest cost size is EP13. If you go smaller, it will be more expensive. 

    The following reference design is a small form factor, which uses the TPS23758 which as primary side regulation. That will get you the smallest layout size for isolation. 

    https://www.ti.com/tool/TIDA-010083

    Otherwise, you can look at our buck solutions. We also have a buck for the TPS23755. 

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

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments