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Computer USB Reverse Current Limit

I'm designing a board that is provided power by an external batter (6V to 24V) or USB. I DC/DC buck the battery down to 5V and use the TPS2113 to select the appropriate power source.

I protect my USB power from reverse currents, however my design will have the option of plugging into an Arduino Uno R3 (Schematics). The Uno has a funky power scheme that really makes it tough to power from my board's 5V line. I've eliminated all cases of reverse conduction when the Uno is plugged in except ONE case. That is:

My board gets USB power and provides it to the Arduino 5V pin and the Arduino is powered off USB. Essentially this means two USB ports are in parallel.

 * Is it safe to assume that two USB's in parallel from the same computer will not fight?

 * Is it likely that both boards plugged into different computers will fight each other? The arduino has a 500MA PTC fuse which helps... but.

I'd prefer to protect against this but I can't change the Arduino's power scheme, I must live with it. Any thoughts?

  • Hi,

    I apologize that no one has followed up with your question. I'm going to close this thread, but if you still have a question please feel free to post a brand new thread instead of replying to this one. We will do our very best to respond within 24 hours to any new post you might have :-)

    Best Regards,
    Aramis P. Alvarez