How much is the 5v pin good for?

Does anyone know how much power I can safely use out of the 5v pin on the "power" header of an Arduino mega? Don't want to over tax the little sucker and kill it! Been looking everywhere and have not found the info yet. Hopeing you can help.


The answer depends of if the board's power is being sourced from the USB connection or the external power jack. You can draw more +5vdc current if you are using the external power input. USB current is limited to anywhere from 100ma to 500ma depending on who you ask. It's not clear to me if the serial converter chip, FT232RL, being used does the needed negotiations for more then the default 100ma USB current limit.

If using the external power source then the 5vdc current would be limited by the current rating of the reverse isolation diode or the combined current limit of the 2 5vdc 800ma voltage regulators, minus what ever 5vdc current is consumed by the board itself.

So as you can see it is a little difficult to give you a specific answer to how much +5vdc current is available for use external to the board.


Well yes, I can see that Lefty 8-) but you did provide much more info than I had! Thank you very much!


What are you trying to control?

Its worth adding to lefty's comments that the onboard regulators do not have heat sinks so will provide much less current then their rated capacity.