I am working on a project that has LIPO battery and a USB as a power inputs. The system should use the battery but if the USB cable is plugged it has to use that as a power source instead of the battery.

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The design is mostly based on Adafruit ESP32 feather https://cdn-learn.adafruit.com/assets/assets/000/041/630/original/feather_schem.png?1494449413. If I understand it correctly the MOSFET is turned off if V_USB is < than V_BATT.

I plan to have this board assembled by JLC PCB and both the MOSFETs and the Schottky diode are extended parts. I want to replace them by basic parts to make it cheaper so I'm looking for alternative parts, Are B5819W and AO3400A adequate replacements in this case?


1 Answer 1


AO3400A is a N-channel MOSFET while the DMG3415U shown in the diagram is a P-channel device. So, no, the AO3400A is not suitable as a substitute.

I don't see any problem with using the B5819W diode as a substitute. Given it's function in the circuit, it should do fine.

The AO3401A given in the comments is indeed a P-channel device and looks like it is suitable. It has a bit higher ON resistance at around 5Vgs, so it'll dissipate a bit more power but nothing significant.

  • \$\begingroup\$ You are right, AO3401A \$\endgroup\$
    – Marc
    Nov 1, 2020 at 19:12

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