A Balancing Strategy and Implementation of Current Equalizer for High Power LED Backlighting

This paper presents a current equalizer to balance the driving currents for high power LEDs (light emitting diode). The proposed strategy combined PWM strategy and digital dimming control to achieve the same illumination for each driven diodes. To obtain the same average current, the duty cycle of LEDs is modulated according to its current amplitude instead of traditional current amplitude adjusting. Complete mathematical analysis and design considerations are detailed. The experimental results are close to the theoretical predictions, and the measured tolerance errors are all below 4%.