随着大功率LED性价比的提高,输出光流量的增加,使LED应用在汽车前照灯成为可能.在输入电压在10～14 V之间变化,负载采用8颗700 mA大功率白光LED的条件下确定驱动方式、拓扑结构和调光方式,设计一种基于LTC3783芯片PWM控制LED亮度的恒流LED汽车前照灯驱动电路,并用LTspiceIV软件对电路进行了仿真.结果表明,输入电压在10～14 V变化时输出电流为一个710 mA均值,有0.7%纹波的电流,电流精度为2.1%,输出电压为28.6 V,输出功率为20 W,电路转换效率为91%.有PWM信号输入时,电路输出一个与PWM信号相同占空比的电流.通过调节PWM信号的占空比实现LED亮度的控制.%With the improvement of cost-effective and increase of output light flaw, the high-power LED used in automobile headlamps becomes possible. A constant current LED array driver used as automotive headlamp based on LTC3783 chip is designed, which considering the drive mode, topology and dimming means. An automotive supply voltage was used as input voltage, and the drive used 8 white high power 700 mA LED in series. The circuit simulation results with LTspiceIV software show that the output currentis a mean of 710 mA, with 0. 7 ％ ripple current when the input voltage changed from 10 to 14 V, the current accuracy is 2. 1％ , the output voltage is 28. 6 V, the output power is 20 W, the circuit conversion efficiency is 91％. And while there is PWM signal, the output current can be changed with the PWM signal, and they have the same duty cycle.
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