摘要:本章詳細介紹了LED燈的工作原理及LED燈驅動芯片的工作原理。近幾年LED燈的發展十分迅速，已經慢慢在汽車前照燈方面進行普及了，而高亮度的LED燈對迎面而來的汽車里的駕駛員可能造成視覺上的影響。因此，必須控制好遠近光燈的開閉，市面上的汽車前照燈多是手動控制遠近光燈變換方式，而本文設計的是夜間自動變更遠近大燈的LED驅動電路。

　　　本電路選用的是NE555驅動芯片，負載是使用4個2.2W的LED燈。通過光敏電阻器利用半導體的光電效應制成的一種電阻值隨入射光的強弱而改變的電阻器；入射光強，電阻減小，入射光弱，電阻增大的原理實現遠近燈的自動變換。還利用繼電器參與電路的控制。

　　　本文設計先對NE555驅動芯片進行了介紹，對其每一個引腳進行了分析，然后對光敏電阻的工作原理進行介紹；還對兩個電路進行了分析與研究，MAX5033驅動電路及某汽車夜間自動變換電路，在這兩個電路的基礎上進行改進，最后設計出LED汽車前照燈驅動電路。

關鍵詞：LED汽車前照燈，NE555，光敏電阻

Abstract:This chapter introduces the working principle of LED lights and LED lamp driver IC works. In recent years, rapid development of LED lighting, has gradually spread in the automotive headlamp aspects, while the high brightness of the LED lights on the oncoming car's driver may cause the visual effect. Therefore, a good distance to control the light of the opening and closing, the market is manual control over Headlamp Light distance transform, rather this is designed to automatically change the distance at night the LED drive circuit headlights.

　　　This circuit is the NE555 driver chips used, the load is to use four 2.2W LED. Through the photosensitive resistor made use of the photovoltaic effect of a resistance to change with the incident light intensity of the resistor; incident light intensity, resistance decreases, the incident light weak, the principle of increasing resistance to achieve the automatic distance light transformation. Also use relay to participate in the circuit of control.

　　　This article is designed for the NE555 drive chip, on every pin is analyzed, and then on the photoresistor works; also on two circuit analysis and research, MAX5033 driver and vehicle automatically transforms circuit, at night the two circuits of improvement, eventually LED headlamp driving circuit.

Keyword: LED Headlamp， NE555， photosensitive resistance