Research And Design Of The Driving Power Supply In Automobile LED Turn Light

With the emergence of high brightness LED(light-emitting diode), it gradually enters the field of lighting as a new light source, leading a new generation of lighting revolution. Because LED has many advantages, it is also popular in automobile lighting industry. LED is being slowly introduced into the automobile field. As the key safety component of the vehicle, the turn light plays an important role in the vehicle active safety.So it will be the future development trend to apply the high performance LED in the turn light.Because of LED’s unique electrical characteristics, it requires a special driving power supply. Therefore, the LED driver used in vehicle is a hot topic in the current automobile lighting application. A stable performance of automobile LED lighting system requires a stable output and high reliable LED driving power supply.This artical introduced the LED’s operating principle and existing LED driving power supply theory on the basis of the LED light-emitting principle. According to the practical applied environment in the field of vehicle, it analyzed a various connecting modes and the main driving methods of LED in detail. In this artical, the typical circuit of the LED lighting driver is summarized. Based on the Buck-Boost topology and the chip of TLD5097, a constant current driving power supply of LED turn light was designed. The designing process of the driving circuit was described in detail, at the same time the designing parameters were given. The reliability of LED driving power supply was analyzed in detail and several factors that affecting the reliability of the power supply were listed. The EMC performance of LED driving power supply was improved through the analysis and improvement of the PCB loop. A thermal protecting function was designed by using the pin function of the driving chip and the purpose of protecting the functional components was realized. The rationality of the design was verified by the experimental prototype. The output open protection and input protection of anti reverse connection were designed by using protecting pins of the chip. The experiment had been carried out on the sample to verify the effectiveness of the protecting function, so that the driving power supply can meet the actual requirements.The experimental prototype was made in this design. Through the experiment, some performance was verified, such as constant current output, high precision current, low ripple, low noise, LED open protection and over temperature protecting function. A high performance of LED driving power supply with constant current was completed. It realized the high efficiency, high performance and high reliability of the system, which can meet the requirements of the automobile electronic applied environment.