Switching Power Supply has three kinds of control circuits: Pulse Width Modulation (PWM), Pulse Frequency Modulation (PFM), Pulse Width and Frequency Modulation (PWM-PFM).

• 开关电源有三种控制方式：脉冲宽度调制(PWM)、脉冲频率调制(PFM)、脉冲宽度频率调制(PWM-PFM)。