1268 results about "Synchronous rectifier" patented technology

A controller for a power converter and method of operating the same employable with a bridge rectifier having first and second synchronous rectifier switches. In one embodiment, the controller includes an amplifier configured to enable a turn-on delay for the first synchronous rectifier switch. The controller also includes a discharge switch having first and second switched terminals coupled to gate and source terminals, respectively, of the first synchronous rectifier switch and configured to discharge a gate-to-source capacitance of the first synchronous rectifier switch to enable a turn off thereof.

A synchronous full bridge rectifier is controlled to provide a power factor near unity. The full bridge rectifiers are transistors each with a controlling input. The AC input signal and currents within the circuit are sensed and sent to a controller. In response, the controller output control signals to turn on / off the rectifying MOSFETS on a timely basis to form a power factor of near one with respect to the AC input signal. The full wave rectifier is made of N-channel MOSFET's, some with fast body diodes. The MOSFET's are rectifiers and PFC control elements. The result is a one stage synchronous rectifier with PFC. A solid state precision analog differential amplifier senses the AC line waveform and high frequency current transformers sense the currents. The controller accepts the inputs of the amplifier and the sensed currents and outputs control signals that turn on and off the four MOSFET's. The timing of turning on / off is arranged so that the current drawn from the AC source is sinusoidal and matches the phase of the sinusoidal AC source.

A synchronous rectifier PWM (SR-PWM) controller controls a MOSFET in response to the value of a secondary current and the status of a synchronous signal for both discontinuous and continuous operation mode. The secondary current is generated in a secondary circuit and is detected by two threshold-detection terminals of the SR-PWM controller. The SR-PWM controller produces the synchronous signal by detecting a switching signal of the transformer via a detection terminal of the SR-PWM controller. Furthermore, a delay-time is inserted after the MOSFET is turned off and before the next switching cycle starts to ensure a proper operation of the MOSFET. In one embodiment, an equivalent series resistance (ESR) of an output capacitor can be used as a sensor to detect the secondary current. Therefore, no additional current sensor is required.

A DC-DC flyback converter, includes a three-winding transformer; a primary power circuit having a first MOSFET connected to a first winding of the transformer; a secondary power circuit connected to a second winding of the transformer terminals; and a self-driven circuit connected to a third winding of the transformer. The secondary power circuit includes a synchronous rectifier in the form of a second MOSFET and the self-driven circuit further includes a delay drive circuit, an isolation differential circuit, a negative removal circuit having a third MOSFET and a synchronous rectifier trigger switch-off circuit for switching the synchronous rectifier to an off condition.