An electronic device is provided comprising a driver for light emitting semiconductor devices. The driver includes a first MOS transistor (MN1) coupled with a channel to the light emitting semiconductor device at an output node. The first MOS transistor (MN1) is configured to determine a current through the light emitting semiconductor device (LED). A control loop is provided so as to control the first MOS transistor to maintain the magnitude of the current through the light emitting semiconductor device at a target value when a voltage drop across the first MOS transistor (MN1) changes. A second MOS transistor is coupled to the output node and biased so as to supply an auxiliary current to the output node, when the voltage drop across the first MOS transistor drops below a minimum voltage level and a feedback loop is provided to reduce the current through the light emitting semiconductor device by an amount proportional to the auxiliary current.