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TPS2372: POE Splitter chip select.

Caspar Lai
Intellectual 380 points
Part Number: TPS2372
Other Parts Discussed in Thread: TPS2373,

Hi Sir:

I want use TPS2372-4 or TPS2373-4 design IEEE802.3bt PD splitter product.

I already get the compare table below.

But I'm still not so sure about those different spec define.

1. About "(PSE Inrush)& (Start-up)(auto-class)"item. It's mean TPS2373 not met 802.3bt(draft) define?right?

2. If I want design PD spilitter product (spec below). Do you have any suggest to select TPS2373 or TPS2372 IC?

  • PSE 54V/90W input
  • this PD product DC 12V/about 70~80W output  

 Thanks!

  • 0
    TI__Expert 5615 points

    Casper,

    Both the TPS2373 and TPS2372 meet the IEEE 802.3bt standard (which is no longer a draft, it is published here!).  The only differences are as you outline above and can be reviewed in the following video.

    In summary, we generally recommend the TPS2373 for most customers.

    The TPS2372 is a better choice if:

    • Autoclass is required
    • Designing for a dual PoE input application
    • Using off-the-shelf DC/DC modules
    • Only PG needed to enable DC/DC module
    • Utilizing a non-isolated power stage (like lighting)
    • Designs which include the following features:
      • Forced UPOE feature, and/or
      • Hitless Failover feature (example: 2 separate CAT-5 cables, 2 PD IC’s and 1 DC/DC)

    These customers do not need to pay for the Advanced Startup feature included in TPS2373.  If wanting to learn more about the Advanced Startup Feature, please watch the video hyperlinked here.

    One final comment is that the IEEE 802.3bt standard supports up to 80W sourced and 71W at the input to the load (after discounting for cable resistance over 100m).  You mentioned the need for "70-80W output at the load" above - which confused me.  Please clarify if requiring greater than 71W at the PD load input and we can discuss a non-standard solution with you.

    Let us know if needing further assistance and thank you for considering PoE products from Texas Instruments.

  • 0 in reply to Thomas Lewis
    Intellectual 380 points

    Hi Thomas:

    Thanks for your reply.But follow TPS2372 & TPS2373 compare table.

    About "autoclass". I don't understand "auto-class" function.

    Could you please depiction detail for this function?

    Thanks!

    Caspar

  • 0 in reply to Caspar Lai
    TI__Expert 5615 points

    Caspar,

    The following video, "Understanding Autoclass in TI's IEEE802.3bt Powered Devices (PD)," should provide you the detail you are looking for here.  After you watch it, let me know if anything remains unclear.

    Thank you for considering PoE products from Texas Instruments,

  • 0 in reply to Thomas Lewis
    Intellectual 380 points

    Dear Thomas:

    Thanks for your information.

    It's very clear.

    Thanks again.

    This question close.

     

    Caspar