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TPS54561 - redundant supply -

Christoph Klees
Prodigy 220 points
Other Parts Discussed in Thread: TPS54561, TPS54560

Hy,

I have to build a redundant supply, that means I have to independent power supplies, each with a TPS54561.

Now I have to connect the outputs of the tps54561 to guarantee a stable power supply if a failure happens.

Normaly both TPS54561 are working.

Can I do this or do I have to protect the IC's ?

 

Kind regards

  • 0
    TI__Guru**** 191445 points

    There is not a direct way to share current between the two devices.  Typically you would connect them together thru OR'ing diodes and set one supply slightly higher output than the other.  Alternately, you could tie the outputs directly together and connect the COMP and VSENSE together.  see this document:

    It is a little tricky to implement and you have to be very careful about your PCB routing.  I have not tried it with TPS54561, but in theory it should work.

  • 0 in reply to JohnTucker
    TI__Mastermind 35165 points

    I have done some basic testing of this with the TPS54560 and the TPS54561 will have the same performance. It sounds like you do not need equal current sharing for this application so I do not expect any issue. Please confirm if this is right.

    When putting them in parallel I recommend placing a local SS/TR capacitor, COMP to GND capacitor and RT/CLK resistor for each TPS54561.

    When I tested this previously the main thing I was looking at was how well they shared current and with testing a few units it was in the range of 1 A of difference between the two. The challenge when trying to have equal current sharing is part to part variations will likely cause one TPS54561 to try to put out more load current for the given COMP voltage.

  • 0 in reply to Anthony F
    Prodigy 220 points
    Your assumption is right, I don't need equal current sharing.
    Thanks for your hints, I will implement them in the schematic / layout!