具高匹配電流與脈波寬度調變亮度控制的白光發光二極體驅動器

White LED Driver with High Current Matching and Pulse-Width-Modulation Brightness Control

楊富國(FU-KUO YANG)

指導教授 ： 黃育賢 ； 陳建中

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00522

摘要

白光發光二極體符合現今全球關注的節能和環保問題，加上體積小且壽命較傳統光源長的特性被廣泛應用於顯示器的發光源，以手持裝置顯示器的背光源使用為最成熟。背光源大都主導電池的使用時間及顯示器亮度與色彩的均勻度。本論文所提之升壓直流-直流轉換器具有較高效率及電流偵測電路能有效降低輸出電流相互匹配誤差，使每一白光LED亮度趨近一致。
整個系統架構是由三大部份組成，分別為(一)升壓直流-直流轉換器主要是將電池電壓升到白光LED所需的電壓，包含了補償器、脈波寬度調變電路、非重疊電路與驅動電路。脈波寬度調變電路是以虛擬雙曲線電流補償電路與環形振盪器組合而成，能較一般鋸齒載波所消耗的功率來的低，將效率提升。(二)輸出電流偵測電路是用電流鏡與運算放大器組成，能降低輸出電流相互匹配的誤差，可使白光LED相互亮度更均勻。(三)白光LED亮度控制電路，可調整所需亮度。
整個白光LED驅動器晶片面積為1.503x1.218mm2不含pads，採用TSMC 0.35um 2P4M 5V的CMOS混合訊號製程來實現。工作電壓範圍在2.7V~3.7V，輸出電壓為4V，最大總輸出電流在105mA，驅動器效率最高可達90%，每一輸出電流兩者相互匹配最小平均誤差可達1.6%。

關鍵字

白光發光二極體 ； 升壓直流-直流轉換器 ； 脈波寬度調變電路 ； 環形振盪器 ； 虛擬雙曲線電流補償電路 ； 電流偵測 ； 亮度控制

並列摘要

The use of white LED can accord with the current issue in energy saving and environmental protection in the world. Due to the features of small size and longer life, this LED is widely used in the backlight of portable device display. The backlight can change the life time of battery and the brightness of display. In the thesis, switching mode boost DC-DC converter can make higher efficiency, and current sensing circuit can increase current matching of each output, and make the brightness of every white LED lightbulbs uniform.
The structure of whole system is consisted of three major parts:(1) Boost DC-DC converter will offer the voltage for white LED, and the circuit includes a compensator, a pulse-width-modulation, a non-overlapping circuit and a driver circuit. The pulse-width-modulation circuit is composed of ring oscillator and pseudo hyperbola charge current generator, and it can enhance the efficiency because the power consumption is lower than sawtooth generator. (2)Current sensing circuit is composed of current mirror and operational amplifier. (3)White LED brightness control circuit can be adjusted to the suitable brightness.
White LED driver is implemented by TSMC 0.35μm 2P4M CMOS 5V process and whole chip area is 1.503x1.218mm2 without pads. The range of the operation voltage is from 2.7V to 3.7V, and the output voltage is 4V. The output maximum current is at 105mA, the driver efficiency will reach to 90%, and the minimum mean error of each output current can reach to 1.6% matching.

並列關鍵字

white LED ； boost dc-dc converter ； PWM ； ring oscillator ； pseudo hyperbola charge current generator ； current sensing ； brightness control

參考文獻

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