Multi-string LED driver with current balancing

Abstract

The present invention discloses a current-source-output light-emitting-diode (LED) driver based on LCLC circuit to provide a constant output current regardless of variations in LED parameters. In the LCLC circuit, the number of additional capacitors is scalable with the number of LED strings for current balancing. Moreover, the input impedance of the improved LCLC circuit is designed to be resistive at the operating frequency to minimize reactive power. The conventional duty cycle control can easily incorporate zero-voltage-switching (ZVS).