I'm designing a board that implements a USB hub. The upstream port will be connected to an Android tablet (or something like that) and the downstream ports will feed some other devices.
The board itself will be self-powered from a battery and related dc-dc circuit so I don't need to draw current from the upstream port.

The question is can I provide current to the upstream and downstream connected devices to power/recharge such devices?
The answer is true for downstream ports but I never found an application note providing backfeed to upstream port (maybe only as an unwanted side effect).

  • \$\begingroup\$ we're talking USB, but not USB-C, right? \$\endgroup\$ Jan 14, 2020 at 21:31
  • \$\begingroup\$ no USB-C it's just an usb 2.0 compliant usb hub \$\endgroup\$
    – weirdgyn
    Jan 14, 2020 at 21:32
  • \$\begingroup\$ Backfeeding 5V into the host can damage some devices. USB-C has special provisions for "backfeeding" via USB power delivery spec. \$\endgroup\$
    – Turbo J
    Jan 14, 2020 at 21:47


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