一种原边控制的小功率反激式LED恒流驱动电路

Design of a Small Power Primary Side Controlled Flyback LED Driver with Constant Output Current

介绍了一种具有功率因数校正功能的原边反激式LED驱动变换器。分析了原边控制的反激式变换器恒流输出的原理与输出电流线性调整率衰退的主要原因;设计了一种自适应的片内功率管关断延时检测与补偿电路,改善了输出电流的线性调整率。设计的单级反激式变换器在90-260V交流输入电压范围内,功率因数大于0.9,输出功率范围为5-13 W。通过采用改进的峰值电流采样技术与内置自适应关断延时补偿技术,输出电流的线性调整率由23.3%减小到小于1.2%。

A primary side controlled flyback LED driver with power factor correction was presented. The principle of primary side controlled flyback with constant output current and the reason of deteriorated line regulation were analyzed. A built-in adaptive power MOSFET turn off delay detection and compensation circuit was designed to improve the output current line regulation. The power factor of flyback converter was always greater than 0.9, and the output power was 5-13 W at the AC input range of 90-260 V. The line regulation could be improved from 23.2% to within 1.2% by introducing an improved peak current sampling technique and a built-in adaptive power MOSFET turn off delay detection technique.