Help with LED.

electricity86 said:

I'd like my UC's GPIO output pin to drive a LED which its VF is 3V min and 3.8V max, and its IF is 20mA.
The GPIO outputs 3.3V (at high level), and can output maximum of 20mA.

Would it be ok to connect the LED to the pin without using a current limiting resistor?
I mean, how can I be sure that the 20mA is not 20mA @ 3V, and that at 3.3V the LED will consume more than 20mA?
Would it damage the GPIO pin?

Thank you in advance.

Click to expand...

electricity86 said:

I'd like my UC's GPIO output pin to drive a LED which its VF is 3V min and 3.8V max, and its IF is 20mA.
The GPIO outputs 3.3V (at high level), and can output maximum of 20mA.

Click to expand...