Rpi power from USB and internal port


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My goal is to be able to power the RPI from either the internal pin or from the usb-c port, but protect the RPI board in case both sources are connected at the same time.

I’m powering a RPI 4 via the 5v pins directly on the board. If the pi is also accidentally plugged in to a usb-c cable, both sources would be effectively connected in parallel, which will fry the board.

Is there a circuit that can detect that there is already voltage coming in from the 5v pin, and if so, block the internal power source from supplying voltage to the pin?



asked 1 hour ago

aim4min's user avatar


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  • For Rpi W (I think similar for other Rpi’s), the USB power is isolated/protected from the External power by a Zener diode. See the following schematic from Rpi W datasheet (more details in Chapter 2): imgur.com/a/WIA7VSy. – tlfong01 18 mins ago   Delete

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