• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 64 subscribers
  • Views 378 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

PoE line topology

Matteo Baldi
Prodigy 60 points
Other Parts Discussed in Thread: TPS2372, TPS2372-4EVM-006, TPS23861, TPS23881

Hello,

I am developing device for PoE line topology and I would like to know if you have already done that before ? If yes, it is possible to share your schematic ?

Thank you in advance,

Matteo Baldi

  • 0
    TI__Expert 5615 points

    Matteo, I assume by "line topology" you mean daisy chaining (having 1 'load' pass on residual power to a subsequent load)?

    If so, yes, we do have some experience here.

    What end equipment are you looking for an example?  It appears you are writing from a University so I am curious to know if you are partnered on a project with a sponsor company as well.

    Thanks,

  • 0 in reply to Thomas Lewis
    Prodigy 60 points

    Hello Thomas,

    Yes you are right, I mean un daisy chaining. The project is to make a sensor network with Powerlink communication and I need to insert PoE to limitate the number of wire.

    I'm in the R&D group of the University and this is a contract project from a extern company.

    More precisely, I would like to know if I can recover the 48V from the chip PD to the chip PSE for the next device or will it mess up the detection and classification phase ?

    I hope hearing from you soon if this was clear enough.

    Best regards,

    Matteo

  • 0 in reply to Matteo Baldi
    TI__Expert 5615 points

    Thank you for the confirmation Matteo.

    Our PoE Application Engineer, Darwin Fernandez, will reply to you within 24 hours from now.

    Thanks,

  • 0 in reply to Thomas Lewis
    TI__Mastermind 41770 points

    Hi Matteo,

    Yes you can, majority of the pass through designs I've seen will use the VDD-RTN (48V) of the PD as the power source of the output PSE. Note, as you go down the daisy chain, this voltage will drop. So within a specific number of chains can the PSE be technically compliant to the standard; however, if you know the chains will always be connected to those specific PDs, then depending on the PD controller you use (majority will use BT PD like the TPS2372 maximize the number of chains) and length of each CAT5e cable on the chain, you can continue the chain as long as the voltage is above the UVLO of the PD controller. For the TPS2372 it is 40V.

    If you want to evaluate a solution, I recommend taking the TPS2372-4EVM-006 and pair it with the TPS23861 (Type 2 PSE) or TPS23881 (Type 4 PSE) EVMs to test out the chaining at a system level under your designing/testing requirements. Thanks!