具有電磁干擾抑制與溫度補償之多通道LED驅動系統晶片之設計

The Design of an EMI suppress and Temperature Compensation Multi-Channel LED Driver System IC

曾榮泓(Jung-Hung Tseng)

指導教授 ： 劉萬榮

國立臺北大學/電機資訊學院/電機工程研究所/碩士(2011年)

摘要

本論文提出改良式LED驅動電路(8通道，每通道30 mA)，具有電磁干擾抑制與溫度補償特性，電流平衡電路採用增益提升架構增加通道輸出阻抗，降低供應電壓變化造成驅動電流變化，並以NMOS電阻取代一般源極退化電阻。低電壓供應電路利用電阻與NMOS電阻產生較低參考電壓，並創造與電流平衡電路具有相同的溫度特性，最後藉由調整能隙電路的溫度係數達到驅動電流的溫度補償，在暗度控制電路中加入了展頻的技術，使脈波寬度調變訊號頻率微幅變動，平均分散主基頻能量，降低電磁干擾。 本晶片使用台灣積體電路公司(0.35μm 2P4M CMOS製程)模擬與實現，溫度於-30 ℃至95 ℃變化範圍內，最大驅動電流誤差0.2 mA，暗度控制訊號頻率於185 KHz至215 KHz變化，驅動電流主基頻能量降低14 dB，總晶片面積為1.57 × 1.46 mm2。

關鍵字

LED驅動電路 ； 電磁干擾 ； 溫度補償 ； 電流平衡電路 ； 暗度控制 ； 脈波寬度調變

並列摘要

This paper presents EMI suppression and temperature compensation techniques with LED driver. The current balance strategy is built up by gain boosting for enhancing the output impedance and restrain the inaccuracy caused by the driving current variation. The resistor in source degeneration is replaced by a NMOS that is biased in linear region.Low voltage supply is produced by a resistor and an NMOS for a reference voltage and as similar as the characteristic of current balance schematic holds. Meanwhile make the driving current temperature compensated by temperature coefficient adjustment. EMI techniques are adopted in the dimming function block that make the frequency of PWM signal influctuating slightly, and separate the energy in the fundamental frequency averagely for EMI reduction. This chip is fabricated and simulated by Taiwan Semiconductor Manufacturing Company (0.35μm 2P4M CMOS). Operating in from -30 ℃ to 95 ℃, 0.2 mA driving current deviates .the dimming control signal is controlled by the frequency from 185 KHz to 215 KHz, and driving current in the fundamental frequency is reduced by 14 dB. the total chip area is 1.57 × 1.46 mm2.

並列關鍵字

LED Driver ； EMI ； Temperature compensation ； Current Balance ； Dimming Control ； Spread spectrum ； PWM

參考文獻

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