Here is the scenario: I have a project needing 3 supply powers:

  • 3.3V to run the microcontroller (max 100mA)
  • 5V to run a bunch of adressable LEDs (max 8A, the most current intensive)
  • 12V to supply op amps (max 15mA x 6 = 90mA for all opamps supplies)

The question is: if I want to use only one power adapter brick to power this thing, is it more logic to use a 12V power supply and step down to 5V and 3.3V? Or is it better to use a 5V power supply since most of the current is used on this voltage and simply step-up to 12V for my opamp needs?

Note: All opamps are signal level, the 12V is to have maximized headroom to preprocess my analog signals.


1 Answer 1


Assuming a generous 90 percent efficiency, that's still 45 Watts in for 40 Watts out, so a 12V supply just to bring it down to 5V would not be efficient compared to stepping up at 80 percent efficiency for 1.5W in 1.2W out 5 Watts vs 0.3W efficiency penalty. Even if you boost to say 14V and use a LDO for a cleaner signal for your OP amps, your still looking at 10 times worse power loss with a 12V supply.

Cost is negligible for supplies for 12V 5A or 5V 8 to 10A, but a 45 watt step down converter will cost more than a 1 watt step up converter.

So in my opinion, it makes more sense to go with your natural voltage need.

  • \$\begingroup\$ Ok cool pretty much what I was thinking. Thanks for the answer! \$\endgroup\$ Nov 18, 2018 at 8:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.