Abstract: An X-capacitor discharge method applied to a switched-mode power supply, wherein the switched-mode power supply comprises an X-capacitor, a rectifier circuit and a switching circuit; the X-capacitor discharge method comprises: arranging a first diode, wherein an anode of the first diode is connected to a first end of the X-capacitor, and a cathode of the first diode is configured as a first node; when it is detected that a voltage of the first node is higher than a first voltage threshold, pulling down the first node through a first sampling current, and performing a timing; and if a time for which the voltage of the first node continues to be higher than the first voltage threshold reaches a first threshold time, pulling down the first node through a first pull-down current. An X-capacitor discharge circuit applied to the switched-mode power supply is provided.

Abstract: A synchronous rectification control circuit and method, and a flyback switched-mode power supply (SMPS) are provided. A voltage adjustment circuit is used to adjust a value of a first voltage signal that represents an output voltage, such that a voltage-second product of a difference between the output voltage and a drain-source voltage of a secondary-side synchronous rectifier can be zeroed in time in a transient process, and no false accumulation occurs. In this way, when a primary-side transistor switch is turned on, the secondary-side synchronous rectifier is turned off, to avoid a case in which the primary-side transistor switch and the secondary-side synchronous rectifier are simultaneously turned on.

Abstract: A frequency regulating circuit for a switching circuit, a frequency regulating method, and the switching circuit are provided. The frequency regulating circuit includes a charging current generating module configured to receive a first signal characterizing an output power and a second signal characterizing an input voltage to generate a charging current and a signal generating module configured to output a third signal according to the charging current. The third signal is used to adjust the maximum operating frequency of the switching circuit so that the maximum operating frequency decreases with the increase of the input voltage. Therefore, the frequency regulating circuit increases the maximum operating frequency of the switching circuit under the condition of low voltage input, which decreases the maximum operating frequency of the switching circuit under the condition of high voltage input to reduce the switching loss of the switching circuit with wide input voltage and improve efficiency.

Abstract: An X-capacitor discharge method applied to a switched-mode power supply, wherein the switched-mode power supply comprises an X-capacitor, a rectifier circuit and a switching circuit; the X-capacitor discharge method comprises: arranging a first diode, wherein an anode of the first diode is connected to a first end of the X-capacitor, and a cathode of the first diode is configured as a first node; when it is detected that a voltage of the first node is higher than a first voltage threshold, pulling down the first node through a first sampling current, and performing a timing; and if a time for which the voltage of the first node continues to be higher than the first voltage threshold reaches a first threshold time, pulling down the first node through a first pull-down current. An X-capacitor discharge circuit applied to the switched-mode power supply is provided.

Abstract: A synchronous rectification control circuit and method, and a flyback switched-mode power supply (SMPS) are provided. A voltage adjustment circuit is used to adjust a value of a first voltage signal that represents an output voltage, such that a voltage-second product of a difference between the output voltage and a drain-source voltage of a secondary-side synchronous rectifier can be zeroed in time in a transient process, and no false accumulation occurs. In this way, when a primary-side transistor switch is turned on, the secondary-side synchronous rectifier is turned off, to avoid a case in which the primary-side transistor switch and the secondary-side synchronous rectifier are simultaneously turned on.