- 學位論文
具動態斜率補償之峰值電流模式升壓轉換器設計
A Peak Current Detect Booster Converter with Dynamic Slope Compensation
摘要
摘 要 現代許多攜帶式消費電子產品都有液晶螢幕顯示器，且都需要背光源為其照明，而背光源大多選擇使用白光LED。白光LED導通電壓約為3V~4V之間，因特性關係一般皆以串聯方式使用，而電源來源的鋰電池電壓也大約在2.5V~4V之間，為穩定背光照度，因此常以升壓轉換器(converter)作為白光LED驅動器。基於此項需求，本文晶片以TSMC 0.35um 2P4M製程為基底，設計20mA定電流源升壓轉換器(Boost converter)，推動兩個白光LED。該電路採峰值電流回授及脈波寬度調變(Pulse width modulation) 模式設計，具動態可變斜率補償，可隨輸入電壓或負載變動程度，作適當動態斜率調整，此項電路優點除了可縮短系統恢復穩定時間(recovery time)外，並可減少光源照度變化。晶片規格為輸入電壓範圍在2.5V ~ 3.3V、切換頻率為1MHz、過溫度保護為85°C、過電壓保護8.5V、輸出電流為20mA，並具調光功能。轉換器效率在一個LED負載與2.5V輸入電壓時約為87﹪。
並列摘要
Abstract A lot of modern portable consumer electronics products have liquid crystal display screen, and all of them need the backlight for illumination, the most backlight they choose are white LED. As the turn-on voltage of white LED is between 3V to 4V, and mostly we used LED in series because of it’s characteristics, but lithium battery power voltage is between 2.5V to 4V, for the sake of backlight illumination stably, we used boost converter to drive white LED. Based on the needs of this chip, we applied TSMC 0.35um 2P4M process for the base to design 20mA constant current boost converter to drive two white LED. With the peak current feedback circuit and pulse width modulation mode converter is designed, and with dynamic slope compensation, which can be adjust slope as input voltage or load change. The advantages of this circuit can not only reduce the system recovery time, but also reduce the variation of light illumination. The specification of chip is 2.5V to 3.3V input voltage range, 1MHz switching frequency, 85℃over temperature protection, 8.5V over-voltage protection, 20mA output current, and a dimming function. While the converter efficiency is about 87% which is at the single LED loaded, and 2.5V input voltage .