I'm new to Arduino, and I'm trying to connect my Leonardo via WiFi using a ESP8266 module. What I want to know is if I can power it directly from the onboard 3.3V pin like in the image:


Or do I need an external voltage regulator? I don't want to damage it. Thanks!

2 Answers 2


The Leonardo is specified to provide only 50mA on the 3V3 pin. A ESP8266 can use up to almost 300mA when transmitting. Consider using a LDO regulator connected to the 5V pin instead.

  • Thanks! And the 5V pin can handle the current? Sep 1, 2016 at 16:15
  • If supplying power via USB it should be fine unless you have a few other devices connected to it. If supplying power via an external 7-12V supply then the on-board regulator may get a bit warm, so you'll have to judge from that. Sep 1, 2016 at 16:19
  • That specification in wrong. The 3.3v regulator is actually 150mA not 50mA. Don't believe everything you read on the Arduino website.
    – Majenko
    Sep 1, 2016 at 16:28
  • Ok, so which one should I trust? I don't want to find out by testing and killing my brand new Leonardo ;) Sep 1, 2016 at 20:28
  • If you're communicating with the ESP8266 for very short bursts then you may be able to get away with the on-board LP2985 if you add a local bulk capacitor. If you need constant communications then you should strongly consider a larger regulator. Sep 1, 2016 at 20:47

Remeber sometimes Arduino board is not delivering sufficient voltage to the ESP8266 module. You can use a 3.3 V ( Do not exceed input voltage from 3.3v) regulator ( AMS1117 ) to power this module.

  • Actually that's the one I've been using. Aaand, I got rid of the Leonardo. I'm programing the ESP module, avoiding the bottleneck of the slower Leonardo's processor. Nov 27, 2017 at 15:47

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