基于自动增益控制(AGC)的高效率LED驱动芯片设计

Design of the High-efficiency LED Driving Circuit Based on Automatic Gain Control(AGC)

设计了一款具有高效率的发光二级管（LED）驱动芯片,采用自动增益控制（AGC）原理,通过内部的峰值电压检测和自动增益调节反馈控制机制,实现幅值稳定、相位相同的正弦包络电压输出,为原边电感电流控制提供比较阀值电压,实现脉宽调制（PWM）耦合的负载恒流输出,进而提高LED发光效率.芯片的工作电压适合于宽电压范围,在交流85～265 V范围内,输出表现了良好的恒流特性,实现高达95％以上的功率因数（PF）值,LED的工作效率达80％以上.

A high-efficiency chip of LED driver is designed. It is got a constant current output of PWM modulate, through technology of the control mechanisms of internal peak voltage detection and the automatic gain adjustment, to achieve a stable amplitude and the same phase sinusoidal envelope voltage output, which supply the comparison threshold voltage for primary side inductor current con- trol by principle of the automatic gain control （AGC）. The operating voltage of the chip is suitable for wide voltage range applica- tions,the output performance of the constant current characteristic has a PF value up to 95 ~, LED work efficiency more than 80 %, within the range of 85 V to 265 V.