A driver for generating an output voltage to power an LED having a minimum operating voltage VLED min, comprising: (a) a first voltage converting stage comprising an input terminal and an output terminal; (b) a charge storage device electrically connected to the output terminal and having a charge output voltage VC; (c) at least one second voltage converting stage having an input electrically connected to the charge storage device, the second voltage converting stage being configured to increase said VC to at least VLED min; and (d) at least one mode controller to switch between at least a first mode and a second mode, in the first mode, the first voltage converting stage charges the charge storage device to power the LED without substantial contribution from the second voltage converting stage, and, in the second mode, the second voltage converting stage power to the LED.