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Rpi Pico VSYS 5V External Power Problem

Power Pi Pico by applying 5 V to VSYS—any experiences with or thoughts on additional safety measures?

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Asked yesterday

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The official Pico datasheet chapter 4.5 suggests using either a Schottky diode or a P-channel MOSFET (P-FET; or a combination of both) when powering the Pico from an external power source (at least if you want to keep the option of simultaneously connecting a computer via USB).

As a suitable P-MOSFET, they suggest Diodes DMG2305UX. However, I couldn’t find this one in online stores here in Germany.

I wondered whether some of you have experiences with one or both of the options and could elaborate what good solutions are and which common diode/MOSFET models are the most suitable for the job (the job being in this case, to power the Pico).

From VSYS and the adjacent GND pin, I power an AirLift FeatherWing to provide the Pico with WLAN, as described in this example. It needs up to 250 mA during Wifi use. Moreover, I want to connect 2 GY-BME280 using i2c and 2 DS18B20 on GPIO 16. These should use something of the magnitude of 1 mA per sensor, which, I guess, is negligible.

The power source will be this 5 V 12 W power supply transforming 230 V 50 Hz AC to 5 V DC.

I attached two images from the original Pi Pico datasheet depicting both versions.

This is their version using the Schottky diode:

Schottky diode version

This is their version using the MOSFET:

MOSFET version

They added: “For inputs that have a low minimum input voltage, or if the P- FET gate is expected to change slowly (e.g. if any capacitance is added to VBUS) a secondary Schottky diode across the P-FET (in the same direction as the body diode) is recommended.”

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edited yesterday

asked yesterday

Manuel Popp's user avatar

Manuel Popp

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