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Driving an led with 2.9V forward voltage drop from 3.3v source

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cksa:
Driving an led with 2.9V forward voltage drop from 3.3v source

What would be a reliable way of doing this? This is just a regular led (in a rgb led). Not of the high power intensity. I'd want around 10-15mA through this.

If i use the regular resistor method, then slight changes in voltage from the voltage source will dramatically change the current going through the led. Is there a simple way of regulating the current? whilst still have it controllable by a GPIO?

Thanks

EEVblog:
If you do the math the current won't "dramatically change" when the source voltage varies "slightly". It will of course if the supply changes from say 3.3V to 5V, or 9V or something, but is that what you expect?
A 3.3V supply is usually very well regulated, so the resistor will be just fine. A constant current driver would be overkill.
LEDs are approximately linear light output with current, so changing your current by even say 10% will have little if any noticeable effect on the perceived brightness.

Dave.

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