An LED driver is a power converter that transforms the power supply into a specific voltage and current to drive the LED to emit light. Typically, the input to an LED driver includes high-voltage AC (mains power), low-voltage DC, high-voltage DC, and low-voltage high-frequency AC (such as the output of an electronic transformer).
The output of an LED driver is mostly a constant current source whose voltage changes according to the forward voltage drop of the LED.
