Patent ID: 6515434
Filing Date: 2003-02-04
Classification: B60Q,H05B,Y10S

Abstract:
A drive circuit for LED arrays comprising:at least two clusters of LEDs, in which one cluster comprises a number of LEDs arranged in series which are connected to a supply voltage, a semiconductor switch being arranged in series between each LED cluster and the supply voltage for allowing LED current to be supplied in a pulsed manner, means for measuring a forward current including a measurement resistor arranged in series with the LEDs in at least one first LED cluster, in a path for the forward current, between the LEDs and ground, and a control loop controlling the semiconductor switch in the first LED cluster referred to as a master cluster such that a constant mean value of the LED current is achieved, wherein the master cluster has a predetermined number X of LEDs in the cluster, the control loop also driving at least a semiconductor switch in a second LED cluster referred to as a slave cluster.