An LED driver is a circuit or module that controls the supply of power to [tag:LED]s. Typically, [tag:constant-current] supplies are used, automatically compensating for variation in forward voltage, while limiting power dissipation or controlling intensity. Typical applications for this tag include: wiring microcontroller or logic pins to drive LEDs; transistors, current sources and switching regulators to drive illumination; and self-contained modules.
LED drivers can be as simple as a resistor to convert fixed voltage to a (reasonably stable) current, or active analog or smps circuits to provide greater flexibility, efficiency, or range of current or intensity control. Drivers can be static (DC), or produce complex sequences for multiplexing (multiplexer), adjustable intensity or color, display of images, and so on. Drivers also include self-contained power supplies that control the amount of current and voltage to an LED light fixture; mains-powered drivers often require a rectifier, or power-factor-correction or other filtering, to produce light free of flicker.