I've a low power consumption regulator to get 3.3V from two 1.5V batteries. I'm going to use it for powering an arduino MKR (MKRFOX1200), so my question is where I should connect it, to the battery connector or directly to VCC.

Looking at schematics it's not clear to me which is the best option in terms of power saving, as VCC seems better but I don't know if it's ok to use that pin to give power

1 Answer 1


You don't really need your regulator. That board has a connection (X1) intended for directly connecting two AA batteries (according to the schematic).

However, if you want to keep it regulated at 3.3V for other reasons (the MCU will happily run from as low as about 1.62V) then sure - use your regulator. But just treat it like batteries regardless. Connect the output of your 3.3V regulator to the battery connector, which goes via the power switching and control circuitry to the 3.3V rail of the board.

  • Yes I want to keep it regulated to 3.3V as sensors as DS18B20 are not happy under 3V, and for some others I need a more accurate potential and less drift than the discharging batteries. I actually have tested both modes, through X1 battery connector and through VCC, and the consumption is identical for the resolution of my multimeter (and under my specs), so I'm going to proceed with X1 battery connector. Thanks!
    – avelo
    Dec 12, 2019 at 13:25
  • 1
    @avelo The only difference between connecting to VCC and to X1 is that X1 is protected against reverse powering (which could damage your batteries) when the board is connected to USB.
    – Majenko
    Dec 12, 2019 at 15:56

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