LED Driver Roundup
LEDs being current, rather than voltage operated devices require special driver circuits for optimal performance. While simple applications like an indicator light that might be run at a fraction of it's rated capability, a series current limiting resistor is sufficient. High power application running at the edge of the LED's max current rating require active regulation to compensate for the negative temperature coefficients of the LED, (measurement techniques are discussed in this university lab paper .) Low power LEDs can be driven with simple series resistor current control when powered from a regulated power supply. The LED Load Line graph be low helps one select a standard resistor value to get the ballpark current setting with a 5 volt power source. Find where your LED's color line intersects the desired current, then pick the closest resistance line below that intersection. (This graph is from LEDnique.com , a collection of basic articles on LEDs aime...