一种省略辅助绕组的隔离型LED恒流驱动设计

One isolated constant current LED drive design free of using auxiliary winding

根据反激式变压器原边和副边的安匝比守恒关系式,可以确定副边电流的最大值;通过副边电流过零检测可以控制副边绕组续流时间和开关周期的比值恒定。在滤波电容的作用下,根据电荷守恒关系,得到恒定的输出电流。这种设计省略了隔离型变压器的辅助绕组,减小了应用系统的成本和体积。

One isolated constant current LED drive design but free of auxiliary wingding is proposed in this paper. Based on the flyback ampere-turns ratio conservation, a constant secondary peak current can be achieved. By the zero crossing detection cir- cuit, a constant ratio between the secondary current time and switching period can also be achieved. In the role of filter and charge conservation, the output drive current is constant. This design solution is free of using auxiliary winding and decreases the cost and size.