I'd like to know how much current can supply the 5V pin and the 3.3V pin on an Arduino Leonardo board. I've been lead not to trust the specs on Arduino's website. And, as an added question, can the 5V pin supply enough power for an LM741 opamp?


1 Answer 1


The 5V pin is either supplied by the USB port, which has a limit of 500mA (imposed by a resettable fuse) if directly connected to the computer or a powered hub (or 100mA in an unpowered hub), or the on-board regulator (NCP1117ST50T3G), which is 1A, when powered externally.

The 3.3V pin is regulated using an LP2985-33DBVR which has a current limit of 150mA (the specifications on the website say 50mA. This is wrong. I think it is a left-over from the old Uno boards with FTDI chips where the 3.3V was fed directly by the internal 3.3V regulator of the FTDI chip and thus limited to 50mA).

Yes, the 5V pin has more than enough current to run an LM741 op-amp.

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    But 5V is a poor supply voltage for a LM741 due to its rather large headroom requirements. Sep 1, 2016 at 21:00
  • @IgnacioVazquez-Abrams You meant to say "But the LM741 is a poor op-amp because of its rather large headroom requirements"... ;)
    – Majenko
    Sep 1, 2016 at 21:01
  • Yeah, that too 😆 Sep 1, 2016 at 21:02
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    @IgnacioVazquez-Abrams I can't recall ever actually seeing an LM741 in a new design in the past 10 years... They still exist for some reason, but I am not aware of anyone in their right mind that would actually use one.
    – Majenko
    Sep 1, 2016 at 21:03
  • It's been a while since I used opamps... I guess I messed up, should have used 358s instead :S Sep 1, 2016 at 21:18

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