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TPS23861: PoE PSE Controller Power UP 2x custom devices at 48V@4A

Abdel
Prodigy 55 points
Part Number: TPS23861
Other Parts Discussed in Thread: LM5122

Tool/software:

Hello,

We are considering the TPS23861 to power up custom devices at 48V.

We have 2 systems and each one has 2 ethernet interfaces. One of the end devices requires up to 4Amps.

  1. System#1 : has 1GBE Ethernet interface and 100MBE interface
  2. System#2 : has 2x 1GBE Ethernet interfaces

Can you suggest the optimal schematic and wiring for these systems and any attention to take into account for the 1GBE requiring 48V@4A.

Thanks,

  • 0
    TI__Genius 15275 points

    Hi Abdel,

    4Amps would translate to 192W (4A, 48V), which is outside the maximum specification for power over ethrnet, therefore using existing PoE architecture would not be possible. You would need to own both ends of the cable and create a prioprietary design in order to do so.

    We have an internal design available where you can achieve 180W that can be modified to support 192W non-standard. Please let me know if this would be of interest and I can guide you for how to achieve. 

    Regards,

    Brandon

  • +1 in reply to Brandon Beader
    Prodigy 55 points

    Hi Brandon,


    Thank you, really apprecite your quick reply!
    The client was asking for 5A@48V, we measured a power consumption up to 3A of the end device.
    This is the reason why we were targetting 4A to make sure that the router will provide enough power to the end device.
    I think it shoulb be fine to lower down the power budget to 3.5A@48V and hope that the end device will not ask for more under some conditions that we did not test so far!

    Yes please share the 180W reference design and the required updates to support 192W non-standard to deliver enough power to the end device.

    We selected the LM5122 DC/DC Boost converter to generate the required power (up to 5A@48V) from the source battery.
    Is this a good companion to this non-standard PoE PSE design? If you have a better candidate we will consider it!


    Thanks,
    Abdel

       

  • +1 in reply to Abdel
    TI__Genius 15275 points

    Hi Abdel,

    Will this device be the only device connected that will consume ~3A? I am assuming the system is designed to have 1 port sourcing, maybe a block diagram would be helpful.

    Please send me a friend request/direct message with your email contact to share with you the design. Then we can make the modifications to allow for higher power. The main consideration for this design would be to ensure that the customer owns both ends of the cable and ensures they follow the design for both the PSE (sourcing) and the PD (sinking) as this is intended for a closed system style design. The two devices will not be operable with other PoE devices on the market. 

    As for DC/DC boost, I am not an expert of those devices so I would recommend posting an additional E2E for their team to take a look at and we can concentrate on PoE specifically in this thread. Slight smile

    Regards,

    Brandon