A multiple-output, bi-directional flyback converter with soft switching of an input switch is disclosed. The primary-side of the converter is comprised of an input power supply, a transformer with a primary winding and a secondary winding, and an input switch with an associated diode, wherein a first end of the primary winding is connected to the input power supply and a second end of the primary winding is connected to the input switch. A first predetermined number of output voltage circuits ar...

Synchronous rectifier circuits are provided for each secondary windings of a transformer. Field-effect transistors of which ON voltage is lower than the forward voltage of a diode are provided in each of the synchronous rectifier circuits. In an energy saving mode, the field-effect transistors in the synchronous rectifier circuit that outputs a diving voltage are turned OFF. A comparator circuit outputs a signal corresponding to a difference between a control voltage output from one of the synch...

A synchronous rectifier control circuit for controlling a synchronous rectifier of a power converter is disclosed. According to one embodiment, the control circuit includes a differentiator circuit responsive to the output voltage of the power converter. The control circuit also includes a summing circuit responsive to an output of the differentiator circuit and a step function signal. The control circuit further includes an integrator circuit responsive to an output of the summing circuit. In a...

A flyback converter with synchronous rectifying function comprises a flyback converter, a controllable unit, a controller and a comparator. The controllable unit is connected to a negative pole of a second auxiliary winding of a secondary winding of a transformer in the flyback converter, a gate of a MOS transistor and an output of the comparator. The controller is connected to the gate of the MOS transistor, the ground and a negative pole of a second winding of a current transformer in the flyb...

A power converter with synchronous rectifying through the control of a current transformer is disclosed. The basic architecture of the power converter includes a flyback transformer (10), a switch controller (20) and a current transformer (30). The secondary winding of the flyback transformer (10) is connected to the primary winding of the current transformer (30) used to control the switch controller (20). The primary winding of the current transformer (30) is connected to a synchronous rectify...

A switching power source device is provided which comprises a secondary MOS-FET 9 connected between a secondary winding 6 of a transformer 2, a reactor 11 connected in parallel to secondary winding 6 of transformer 2 for accumulating energy during the on-period of primary MOS-FET 4, and a secondary control circuit 12 connected to reactor 11 and a control terminal of secondary MOS-FET 9. Secondary control circuit 12 serves to turn secondary MOS-FET 9 off to accumulate energy in reactor 11, turn s...

This invention describes a method for using self-synchronized (also known as self-driven), synchronous rectifiers in converters employing high output voltages or conversely, in converters with wide input voltage ranges.

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. ...

Disclosed herein is a variable-frequency flyback. The flyback converter comprises a flyback transformer having secondary windings for drive and detection for providing first and second induced voltages induced from an input voltage in first and second turn ratios with a primary winding, respectively, a voltage detector for detecting the second induced voltage, a switching controller for determining, on the basis of a level of the voltage detected by the voltage detector, whether a current load s...

A control circuit for controlling the output voltage of a primary-controlled switched mode power supply. The switched mode power supply includes a primary-side switch and a transformer with a primary winding, a secondary winding and a secondary-side auxiliary winding. The control circuit is connected to the auxiliary winding and a voltage tapping point between the secondary winding and the auxiliary winding. The control circuit includes a secondary-side switch and an RC element. The secondary-si...