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).