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 said output terminal and having a charge output voltage VC; (c) at least one second voltage converting stage having an input electrically connected to said charge storage device, said 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 said first mode, said first voltage converting stage charges said charge storage device to power said LED without substantial contribution from said second voltage converting stage, and, in said second mode, said second voltage converting stage powers said LED