Most derivatives are able to sink about 3.2 mA while keeping a valid TTL '0' voltage level (in Port 0; about 1.6 mA in ports 1, 2 and 3). I think that if the pin is used only to drive a LED, the voltage level in the pin is not very important, so you can select a resistor value suitable to get a little higher current, say 5 mA. This will give you enough bright in the LED.

In any case, I agree with Erik, you must look the data sheets for the actual specifications of your particular device. There are two limits (at least) one limit per pin and one limit per port.

Regards,

Alfredo.


to d you can select in your application -driving a LED- the output voltage