摘要:本章详细介绍了LED灯的工作原理及LED灯驱动芯片的工作原理。近几年LED灯的发展十分迅速，已经慢慢在汽车前照灯方面进行普及了，而高亮度的LED灯对迎面而来的汽车里的驾驶员可能造成视觉上的影响。因此，必须控制好远近光灯的开闭，市面上的汽车前照灯多是手动控制远近光灯变换方式，而本文设计的是夜间自动变更远近大灯的LED驱动电路。
本电路选用的是NE555驱动芯片，负载是使用4个2.2W的LED灯。通过光敏电阻器利用半导体的光电效应制成的一种电阻值随入射光的强弱而改变的电阻器；入射光强，电阻减小，入射光弱，电阻增大的原理实现远近灯的自动变换。还利用继电器参与电路的控制。
本文设计先对NE555驱动芯片进行了介绍，对其每一个引脚进行了分析，然后对光敏电阻的工作原理进行介绍；还对两个电路进行了分析与研究，MAX5033驱动电路及某汽车夜间自动变换电路，在这两个电路的基础上进行改进，最后设计出LED汽车前照灯驱动电路。
关键词：LED汽车前照灯，NE555，光敏电阻
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
