應用於液晶顯示器背光之發光二極體驅動器具有動態參考電壓追蹤

Abstract

由於發光二極體廣泛的被應用於各種產品，最近幾年PDA、行動電話、數位相機、NB等可攜式電子產品的液晶顯示器大多改用彩色面板。液晶顯示器本身屬於非主動性發光元件，必需利用背光照明模組照明才能夠讀取面板的影像。

從目前趨勢看來，LED有充分的理由取代現有冷陰極燈管（CCFL）的地位，由於LED背光源符合環保、輕薄、省電與色彩飽和度佳等優勢，特別是在NB面板方面，與傳統的CCFL背光源比較，LED背光源NB面板厚度約為CCFL背光源NB面板厚度的1/2，節能方面，LED背光源NB面板更可較CCFL背光源NB面板節省約20%∼30%之電力.

本篇論文中提出應用於發光二極體驅動電路之電流控制式直流-直流升壓電源轉換電路設計，其輸入電壓為5V，而輸出電壓為35V。其中回授控制電路以脈波寬度調變之方式實現，並根據發光二極體順向電壓改變的回授機制。本論文之設計使用TSMC 0.25um BCD 5V/40V 2P3M CMOS製程技術進行模擬與製作。

In recent year, LED is extensive and is applied to various products, such as PDA, mobile phone, several cameras, NB, etc. Modern display can mostly use the colored panel instead of type liquid crystal display of electronic product, since liquid crystal display is non-self-luminous component. It must utilize backlight module of lighting to read image of the panel. By the look of trend at present, LED has had sufficient reasons to replace the status of the existing cold cathode fluorescent lamp (CCFL). Since LED backlight source has some advantages, it accords environmental protection, light and thin, energy saving and high color saturation. Especially in NB panel, compared with traditional CCFL backlight source, the thickness of LED backlight source of NB panel is about 1/2 of CCFL backlight source in NB panels. In an aspect of energy saving, it can save about 20%- 30% of power consumption. This thesis presents a current mode DC-DC boost converter for LED applications with 5V input voltage and 35V output voltage. The boost voltage regulator uses a pulse width modulation (PWM) with a dynamic resistor and a reference tracking circuit according to the variation of forward voltage of LEDs. The LED driver circuit was simulated and fabricated by TSMC 0.25um BCD 40V process.