Power Supply / USB & DC


Question about using a DC Jack to power the Photon. Do we need to create a jumper configuration as not to have the Photon powered by both USB and DC? Or will the Photon automatically pick the best source?

I am worried that using DC and sending a regulated voltage to the RAW port would cause issues if at the same time the Photon was plugged into a USB port for debugging at the same time.

When working with Arduinos in the past, I’ve always jumpered the ground pin between the DC and the USB power source. Unfortunately, with the Photon, this may not be possible.

Has anyone else looked into this problem or have a suggestion?


There is a series schottky diode to prevent voltage from flowing backwards from VIN to USB. That’s why when you use VIN as a power output, powered by USB, the voltage is 4.8V, not the 5.0V from USB.

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And having a protection diode from your DC jack to the Photon is no bad idea either - for the same reason.

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