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    Powered USB type C hubs and backfeeding?

    Discussion in 'Hardware Components and Aftermarket Upgrades' started by Starlight5, May 6, 2018.

  1. Starlight5

    Starlight5 Yes, I'm a cat. What else is there to say, really?

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    So I have a powered USB type C hub with 5V micro USB power input. I don't have a type C multimeter, so I used a USB 3.1 type C to type A adapter to connect standard type A multimiter, and discovered that the hub definitely backfeeds, making it unsafe to use in this configuration - unless power lane is disconnected, one way or another.

    The question is - when used with 12V or 20V type C power delivery port of a laptop/tablet, will the circuitry inside said power port prevent backfeeding, or not?
     
    Starlight5, May 6, 2018
    #1
  2. Starlight5

    Starlight5 Yes, I'm a cat. What else is there to say, really?

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    Anyone?
     
    Starlight5, May 17, 2018
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  3. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    I don't know for sure but would expect that standard USB circuit design would include blocking diodes to prevent damage due to power flowing the wrong way. Given the negligible cost of surface-mounted diodes it would be careless not to do this. The Power Delivery hardware is cleverer as it involves chips at each end of a link which talk to each other and agree which way the power should flow and at what voltage before the power starts to flow.

    John
     
    John Ratsey, May 18, 2018
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    Starlight5 likes this.