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2 isolated power supplies for TPS2384

Pierre-Olivier Lessard
Prodigy 105 points
Other Parts Discussed in Thread: TPS2384

Hi,

For some design considerations (transfo/coupled-inductor height) I could not support a sole 60W isolated power supply for the PSE TPS2384, I need to separate it in two circuits. Do the TPS2384 P1/N1, P2/N2, P3/N3 and P4/N4 ports are isolated from each others (I guess so)? Does the TPS2384 is supporting an isolated 48V power solution for P1/N1, P2/N2 and an other for P3/N3,P4/N4?

Regards,

Pierre-Olivier

  • 0
    TI__Genius 15685 points
    Hi Pierre-Olivier，

    The DRAIN connects to the controller chip for all four ports, so I don't think the ports are isolated. I am checking with designer regarding your approach. I will get back to you ASAP. Thanks for your patience.

    Best regards,
    Penny
  • 0
    TI__Genius 15685 points
    Hi Pierre-Olivier,

    TPS2384 has been designed for a single 48V input supply to control all four ports. The PSE uses the Px and Nx pins for each port to measure the port voltage and/or current for certain modes. For example, Vport =0V for off mode and Iport = Vport/25K for detect mode.
    If pins P1 and P2 are connected to a different +48V rail than P3 and P4, the internal measurements may be upset resulting in incorrect modes. For example, the 50V rail on ports 3 and 4 are at a higher voltage than the supply rail (48V) and the internal differential amplifier (figure 5 of the datasheet) may not function because it is driven from the lower 48V rail.
    For this reason, we cannot recommend to use separate supplies for ports on a 4 port PSE.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Prodigy 105 points

    Hello Penny,

    Many thanks for the fast reply, I will consider another power solution.

    Regards,

    Pierre-Olivier