This is probably an easy question. When using an STM32 Nucleo powered by a 5V power supply, can I use its 3V3 pin to supply 50mA? Or do I need to use for instance a 3V3 linear regulator attached to my 5V power supply.

Thank you.

  • \$\begingroup\$ Which board are you using? \$\endgroup\$
    – Long Pham
    Commented Jul 16, 2021 at 10:16
  • \$\begingroup\$ The small arduino nano sized one. STMicroelectronics STM32 Nucleo-32 Development Board NUCLEO-G031K8. \$\endgroup\$ Commented Jul 16, 2021 at 10:24

1 Answer 1


The NUCLEO-G031K8 dev board uses a LD39050PU33R regulator to provide 3.3V rail from other high voltage sources (USB 5V for example):

enter image description here

You can use the onboard 3.3V rail to power other devices but make sure not to cross 500mA limit of the regulator.

Here's the NUCLEO-G031K8 schematic for reference.


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