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Anti-parallel hot-swap controllers

Michael Gilge
Expert 1720 points
Other Parts Discussed in Thread: LM5067

We are looking for a load-sharing solution, where power (48V based) can flow between 2 sites in both directions, depending on where power is available. In other words, if site A has power available, it needs to be fed forward to site B. Conversely, if site B has power available it will reverse feed site A. 

We need to safeguard the connection against polarity mismatch or power being available at both ends. Is there something like a dual-direction load share or hot-swap controller? 

Thanks, Michael

  • 0
    TI__Genius 12621 points

    Hi Michael,

    I can think of a couple concepts but will discuss with our team members for a second opinion, who will be returning next week.

    In the meantime, would you prefer a high side switch (+48V system to break the positive connection and have GND remain), or a low side switch (a -48V system to break the neg voltage connection and have the RTN line remain)? Or if either is ok, breaking the low-side connection may be more cost effective.

    Thanks,

    Alex

  • 0 in reply to Alex Triano
    Expert 1720 points
    Hi Alex,
    thanks you. we would prefer a low side switch for 2 reasons: cost and it has to work in connection with a PoE supply, which is all low side.
    --Michael
  • 0 in reply to Michael Gilge
    TI__Genius 12621 points

    Hi Michael,

    For reference, here is a solution for the LM5067 with input reverse polarity protection.

    I would think you can copy the input side FET and zener protection circuit and mirror it on the output side.

    The LM5067 in between would limit inrush current in one direction. It can allow current in the reverse direction, but without inrush or current limiting.

    If ON/OFF control is needed in both directions, you can probably add a second back-back FET on the LM5067's GATE output.

    If protection (inrush limiting and current limiting) is needed in both directions, then the design gets a bit more complicated and I would need to brainstorm it when we have more time next week.

    Thanks!

    Alex