说明：  对PWM控制芯片SG3524与SG3525的工作性能作了介绍和比较，通过实验得出了SG3525在软起动功能上较SG3524有很大的改进。
(PWM control of the SG3524 and SG3525 chip performance were presented and compared with experiments obtained through soft-start function in the SG3525 more significant improvement SG3524.)