Digital Pin Current

Hi

The Atmel documents state the maximum current the Arduino can source on the digital pins is 40ma.
What is the sensible maximum and can it also sink 40ma?

Regards

Ian Eagland

Hi Ian, according to this page: http://www.arduino.cc/playground/Learning/ArduinoSpecs The atmega168 can source and sink 40ma per pin, maximum total current is 300ma

edit: the ATmega168 data sheet says the maximum total current is 200ma and there is some fine print in the section on Electrical Characteristics about further restrictions on combinations of ports. Its worth checking with the data sheet to make sure your app is not exceeding the absolute miximum ratings

Does this (300mA) only apply to the output pins, or to the main 5V output pin as well? I guess it goes directly from the dc regulator to the pin, so what is the max current there?

I wouldnt push the regulator past 200 - 300mA at 12v. It would get pretty toasty without a proper heatsink.

If you want to draw lots of 5v current then its best to get a switching regulator. Linear regulators burn excess energy off as heat. Switching ones dont.