Abstract: A power converting device includes a transformer, a first switch coupled to a primary winding of the transformer, a PWM controller which generates a first PWM signal for controlling conduction and non-conduction of the first switch and which generates a control signal that leads the first PWM signal, a rectifier-filter circuit which rectifies an induced voltage generated by a secondary winding of the transformer, a second switch coupled to the secondary winding, and a synchronous rectifier controller which controls conduction and non-conduction of the second switch, and which controls, according to the control signal, the second switch to become non-conductive prior to conduction of the first switch.

Abstract: A power converting device includes a main switch, a synchronous rectifier switch, a rectifier-filter circuit which outputs an output voltage, and a synchronous rectifier control circuit which includes a sampling circuit coupled to the rectifier-filter circuit for outputting a voltage variation signal, a differential amplifier circuit that outputs an amplified signal by adding the output voltage and an offset voltage to the voltage variation signal attenuated thereby, and a comparison circuit that compares the amplified signal with the output voltage so as to output a trigger signal, such that the synchronous rectifier switch is turned on when the main switch is turned off, and is turned off prior to conduction of the main switch.

Abstract: A power converting device includes a main switch, a synchronous rectifier switch, a rectifier-filter circuit which outputs an output voltage, and a synchronous rectifier control circuit which includes a sampling circuit coupled to the rectifier-filter circuit for outputting a voltage variation signal, a differential amplifier circuit that outputs an amplified signal by adding the output voltage and an offset voltage to the voltage variation signal attenuated thereby, and a comparison circuit that compares the amplified signal with the output voltage so as to output a trigger signal, such that the synchronous rectifier switch is turned on when the main switch is turned off, and is turned off prior to conduction of the main switch.

Abstract: A power converting device includes a transformer, a first switch coupled to a primary winding of the transformer, a PWM controller which generates a first PWM signal for controlling conduction and non-conduction of the first switch and which generates a control signal that leads the first PWM signal, a rectifier-filter circuit which rectifies an induced voltage generated by a secondary winding of the transformer, a second switch coupled to the secondary winding, and a synchronous rectifier controller which controls conduction and non-conduction of the second switch, and which controls, according to the control signal, the second switch to become non-conductive prior to conduction of the first switch.