5 years, 5 months ago.

I wanna know maximum current at 3.3v regulated out pin.

Hi! I wanna know maximum at 3.3v regulated out pin. I need around 500mA totaly as supplying current. I wanna use 3.3v regulated out pin for supplying current to decorders. Although, I don't know its maximumly allowed current.

If it doesn't have enough margin, I have to make a other circuit for supplying current. So I want to know exactly.

Someone knows where it is written about or how much it is? Pls teach me!


Thanks for the question.

I need to know which platform you are using? Then you must consult its data sheet.


Andrea, team mbed

posted by Andrea Corrado 02 Dec 2016

1 Answer

5 years, 5 months ago.

As Andrea said, it depends upon the platform. While it may be in the specifications for some of them for most platforms you'd probably need to look at the schematics and work it out from there. Some (e.g. the LPC1768) have a dedicated voltage regulator for the 3.3V output, others (e.g. the C027) have a series resistor on the 3.3V output making only useful as a voltage reference rather than a power supply.

However if you need 500mA then it's fairly safe to say that none of the boards will be good enough. Realistically the upper limit is going to be in the 100-200mA region. (This is a guess, I may be wrong)

500mA is too much power for a standard USB port, you would need a high power charging port for that much power. And to include a 500mA power supply on an mbed board which needs a couple of mA to run would be massively over engineering things and adding far too much cost for a very rare use case.