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TPS22990: Back feed from output to input?

Keith Brown1
Prodigy 20 points
Part Number: TPS22990
Other Parts Discussed in Thread: TPS2121, TPS22917, TPS22916, LM66100

Hi Gurus!

I'm considering using the TPS22990 as a switch to select between to power supply outputs to a common rail.  My question is, is the device back-feedable?  For example, if there is a voltage on the output while there is no voltage on the input, will the output voltage run through the body diode of the FET show in the function block diagram, page 16 of http://www.ti.com/lit/ds/symlink/tps22990.pdf ?

Then, how do I make sure I am not ordering the part with the option discharge path?

Thanks so much for your insights!

Keith.

  • 0
    TI__Genius 10855 points

    Hi Keith,

    Thanks for reaching out on E2E!

    You are correct, the TPS22990 does not have "reverse current blocking".  In other words, if the voltage on the output of the device is greater than the voltage on the input, then current will conduct through the body diode of the device and feed back into the input.

    We have a few load switch devices that have integrated reverse current blocking, as well as integrated power mux devices which can select between both channels on a single device. For load switches, I recommend looking at the TPS22916, TPS22917, or LM66100. For power mux devices, I would consider looking at the TPS2121.

    We also recently released an app note, Basics of Power MUX, that discusses different switching topologies and the advantages / disadvantages of each.

    Let me know if you have any questions!

    Thanks,

    Arthur Huang

    To find the latest information on Power Switches, visit www.ti.com/powerswitch

    Please click "This resolved my issue" button if this post answers your question.

  • 0 in reply to Alpha H
    Prodigy 20 points
    Hi Arthur -

    Thanks for the prompt info! Unfortunately those ideal diodes are just a bit on the weak side for my application. I may have to look at an SSR or do this discretely.

    Keith.