Abstract: A method of switching operational modes of a power converter includes starting up a primary controller applied to the power converter to make the power converter operate in a normal mode; a secondary controller applied to the power converter detecting an output voltage of a secondary side of the power converter and the primary controller detecting an operational frequency of the power converter; if the operational frequency of the power converter is lower than a predetermined frequency and satisfies a first frequency condition, the primary controller controlling the power converter to enter a sleep mode; and when the power converter enters the sleep mode and the output voltage is lower than a trigger voltage, the secondary controller making the primary controller to control the power converter turned on.

Abstract: A control method is disclosed to have a voltage sample capable of more correctly representing an output voltage of a power converter. The power converter has a primary side and a secondary side galvanically isolated from each other. A feedback voltage is received in the primary side. A main power switch is turned OFF, starting an OFF time, during which the feedback voltage is constrained in response to the voltage sample. In a sampling time within the OFF time, the feedback voltage is sampled to update the voltage sample representing the output voltage in the secondary side. A driving signal is provided in response to the voltage sample to control the main power switch.

Abstract: A method of switching operational modes of a power converter includes starting up a primary controller applied to the power converter to make the power converter operate in a normal mode; a secondary controller applied to the power converter detecting an output voltage of a secondary side of the power converter and the primary controller detecting an operational frequency of the power converter; if the operational frequency of the power converter is lower than a predetermined frequency and satisfies a first frequency condition, the primary controller controlling the power converter to enter a sleep mode; and when the power converter enters the sleep mode and the output voltage is lower than a trigger voltage, the secondary controller making the primary controller to control the power converter turned on.

Abstract: A control method of a flyback power converter includes a voltage detection pin detecting conduction time of a power switch of a primary side of the flyback power converter, a feedback pin detecting conduction time of a synchronous switch of a secondary side of the flyback power converter, the feedback pin detecting a number of inductor capacitor resonant valleys when the flyback power converter operates in a discontinuous conduction mode, and a high voltage detection pin detecting an input voltage inputted in the flyback power converter; and a controller applied to the flyback power converter making the flyback power converter operate in a quasi-resonant mode when the number of the inductor capacitor resonant valleys is greater than a predetermined number, an operational frequency of the flyback power converter is less than a predetermined frequency, and the input voltage is less than a predetermined voltage.

Abstract: A control method of a flyback power converter includes a voltage detection pin detecting conduction time of a power switch of a primary side of the flyback power converter, a feedback pin detecting conduction time of a synchronous switch of a secondary side of the flyback power converter, the feedback pin detecting a number of inductor capacitor resonant valleys when the flyback power converter operates in a discontinuous conduction mode, and a high voltage detection pin detecting an input voltage inputted in the flyback power converter; and a controller applied to the flyback power converter making the flyback power converter operate in a quasi-resonant mode when the number of the inductor capacitor resonant valleys is greater than a predetermined number, an operational frequency of the flyback power converter is less than a predetermined frequency, and the input voltage is less than a predetermined voltage.