應用於行動裝置之多通道LED驅動晶片設計

A multi-channel LED driver for mobile device applications

張建焜(Chien-Kung Chang)

指導教授 ： 劉萬榮

共同指導教授 ： 林道通

國立臺北大學/電機資訊學院/資通科技產業碩士專班/碩士(2013年)

摘要

本研究描述了應用於行動裝置之多通道LED驅動晶片設計，使用台積電0.35微米2P4M CMOS實現。隨著通訊產品和便攜式設備需要更小的尺寸，更低的成本，較低的雜訊干擾和精確電流控制已成為LED驅動器的背光應用的新趨勢。使用低壓差穩壓器電源，輸入電壓為2.7V至4.2V。使輸出固定的電壓為2.5V。設計保證通道電流平衡且誤差小於2％，無論LED的正向電壓的變化都能保持電流控制精度。此外，調光頻率可以設置為10KHz。利用控制週期方式來調整LED亮度，確保電池有更長使用壽命。
總晶片面積為1.89 × 1.7 mm2。

關鍵字

LDO低壓降穩壓器 ； LED驅動電路 ； 電流平衡電路 ； 暗度控制

並列摘要

This research presents a multi-channel LED driver for mobile device applications. With regards to the new trend for backlighting applications in mobile electronics and portable devices; requiring a smaller size, lower cost, lesser noise and more accurate current control LED driver is highly desirable, with this the idea of integrating more than one design features within a single chip is advantageous. The analysis of using a capacitor-less low dropout regulator to power the constant current source has been explored, with the implementation of wide range battery voltage of 2.7V to 4.2V. Possible load current variations were introduced and verified to output a fixed voltage of 2.5V. The design ensure a current matching of less than 1% error current balance and achieve a high accuracy current control of less than 1% error regardless with LED’s forward voltage variation. Moreover, for high end portable device with multimedia applications, dimming frequency can be set to 10 KHz. In addition, a switching output is a better approach for managing LED’s contrast and brightness adjustment as well as maximizing power consumption, ensuring longer life for driving string of LEDs. This design is implemented in 0.35um TSMC 2P4M CMOS process and the chip size is 1.89x1.7 mm2.

並列關鍵字

LDO，LED Driver ； Current Balance ； Dimming Control

參考文獻

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