System General Corporation

Wei-Li Hsu

Ta-Yung Yang

Chou-Sheng Wang

Chien-Yuan Lin

An synchronous rectifying apparatus or synchronous rectifying circuit of a soft switching power converter is provided to improve the efficiency. The integrated synchronous rectifying circuit includes: a power transistor connected from a transformer to the output of the power converter for rectifying; a controller having a latch circuit generates a drive signal to control the power transistor in response to a switching signal generated by a winding of the transformer in response to the switching of the transformer. The controller turns off the power transistor when the switching signal is lower than a low-threshold. The power transistor is turned on when the switching signal is higher than a high-threshold. Furthermore, a maximum-on-time circuit provided in the controller is applied to generate a maximum-on-time signal for limiting the maximum on time of the power transistor.

Synchronous rectifying for soft switching power converters

A power converter and a PWM controller for compensating a maximum output power includes a power switch, an oscillator, a control circuit and a delay modulator. The oscillator generates a pulse signal. The control circuit is coupled to the oscillator for generating a PWM signal and an over current signal in response to the pulse signal and a current sense signal of the power converter. The delay modulator is coupled to the control circuit for generating a delay control signal in response to the PWM signal and the over current signal, wherein the delay control signal is used to prolong a propagation delay time of the control circuit in response to the on-time of the PWM signal, and the propagation delay time can be compensated by the on-time of the PWM signal to limit the maximum output power under a high-line input voltage and a heavy-load condition.

Growing community of inventors

Keelung, Taiwan

Wei-Li Hsu