現今紅光、綠光與藍光發光二極體(RGB LED) 被廣泛應用於高階顯示器之背光以及次世代消費等級之顯示器。而RGB LED優點在於寬廣的色域、可混成白光、高效率之發光性及高調光比例。因為RGB LED之順向導通電壓不同，使用變動匯流排電壓調節器(Dynamic Bus Voltage Regulation, DBVR)可以優化前端電源之設計。
本文提出適用於RGB LED為背光源之驅動系統，此系統由前級之功率因數修正、數位控制LLC諧振轉換器與作為輔助電源之返馳式轉換器所構成。由於LLC諧振轉換器開關切換具有零電壓切換(Zero Voltage Switching, ZVS)特性，因此，大幅降低切換損失，並提升效率。本文所提之可控電壓LLC諧振轉換器輸出電壓可藉由數位變電阻器調整，因此可以維持RGB 發光二極體所需之電流，進而提升驅動系統之效率。本文將詳細介紹此驅動系統之硬體與韌體架構，最後由實驗結果驗證本文所提驅動系統之正確性。根據實驗結果，本文所提出之驅動系統LLC諧振轉換器輸出電壓為可調，其電壓取決於RGB LED燈條所需電壓。

Red, green and blue (RGB) light emitting diodes (LEDs) for backlighting are found in high-end display units as well as next-generation consumer grade displays. The advantages of RGB LEDs include wide color gamut, tunable white point, higher luminance efficacy, and high dimming ratio. Because RGB LEDs have different forward voltages for the red, green, and blue LEDs, dynamic bus voltage regulation (DBVR) can be applied to optimize the power stage design.
In this thesis, a RGB LED backlight driving system is proposed. The proposed system consists of a power factor correction pre-stage, a digitally-controlled LLC resonant converter and a flyback converter auxiliary power supply. The LLC resonant topology allows for zero voltage switching (ZVS) of the main switches thereby dramatically lowering switching losses and boosting efficiency. The adjustable 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. Detailed description about the hardware and firmware parts of the proposed system is presented. Finally, experimental results are presented to validate the correctness of the proposed 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.

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