RGB LED backlight driving system with dynamic voltage regulation capability

Advantages including higher luminance efficacy, local dimming capability, wider color gamut, faster response, longer operation life and lesser environmental issues makes RGB LED backlight system suitable for high-end display units. For RGB LEDs, the forward voltages for the red, green and blue LEDs are different. Therefore, dynamic voltage regulation (DVR) can be applied to optimize the power stage design. In this paper, a RGB LED backlight driving system is proposed. The proposed system consists of a power factor correction pre-stage and a digitally-controlled LLC resonant converter. The output voltage of the presented LLC resonant converter is adjusted by a digital controller so that RGB LED maintains the desired string current; this will improve the efficiency of the driving system. According to the experimental results, the presented system can adjust the output voltage of the LLC resonant converter according to the requirements of the RGB LED string.