Here's some background: I am using an ESP32 Wroom C3 that is powered by a 3.7 V battery using a voltage regulator to step down the voltage to 3.3 V.

My question is: should I use the 3.3 V from the regulator to power the component (3.3 V, 1.5 mA draw), pull from VDD_SPI, or pull from one of the GPIO pins?


From these voltage sources, how should I ensure current is 1.5 mA? I've been told I should use a transistor or use a resistor and diode.

EDIT: Trying to power a PPG (Link)

  • \$\begingroup\$ if the component draws 1.5 mA at 3.3 V, then you ensure the current is 1.5 mA by making sure that the voltage stays at 3.3 V \$\endgroup\$
    – jsotola
    Jul 17, 2022 at 5:57
  • \$\begingroup\$ What kind of "component" are you trying to power? How does it relate to the ESP32 (I/O interface)? These should also guide the solution. Details, please. \$\endgroup\$
    – TypeIA
    Jul 17, 2022 at 6:57
  • \$\begingroup\$ awesome, thanks! @TypeIA I am trying to power a PPG as a sensor to read heartbeat. (Also added link in edit) \$\endgroup\$ Jul 17, 2022 at 21:16

1 Answer 1


It appears VDD_SPI can also be used as a normal GPIO pin (11), if it's not used as an internal flash VDD output. So I think you can handle it as a normal GPIO. And 1.5mA should be fine at any GPIO pin.

For the other question: it would be so much easier if we had a circuit and more details about the components.


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