Niko Semiconductor Co., Ltd.

Ko Semiconductors Co., Ltd.

Hui Chiang Yang

A synchronous rectification circuit with dead time regulation being adapted for a forward power supply to regulate a dead time of a switch circuit is described. The synchronous rectification circuit has a first switch control circuit connected with a first switch to control ON/OFF of the first switch, a dead time regulation circuit connected with the first switch control circuit to produce a dead time regulation signal, and a second switch control circuit connected with a second switch and the dead time regulation circuit to control ON/OFF of the second switch.

Synchronous rectification circuit with dead time regulation

A synchronous rectifier with dead time adjusting function is used in fly-back power supplies for adjusting dead time of switches. The synchronous rectifier has a rectifying circuit connected to a secondary side terminal of a transformer and outputting a positive half-cycle voltage, a charging circuit connected to the rectifying circuit for producing a first charging voltage and a second charging voltage, a regulated power circuit connected to the charging circuit and producing a reference voltage, a trigger circuit connected to the rectifying circuit and the charging circuit for generating a dead time adjusting comparing signal, a comparing circuit connected to the regulated circuit, the charging circuit and the trigger circuit for producing a dead time adjusting signal, and a logic circuit connected to the comparing circuit and the rectifying circuit for outputting a driving signal for controlling on/off states of a first electric switch.

Synchronous rectifier with dead time adjusting function

A current detecting circuit connects to a secondary side of a transformer, including a first, second transistors and a field-effect transistor (FET). The first transistor has a base connecting with the base and collector of the second transistor to form a common base terminal, an emitter forming a first detecting terminal and an emitter forming a feedback terminal. The second transistor has a collector forming a second detecting terminal. The FET is used to replace a prior current rectifying diode. The FET has a source connecting to an output terminal of the transformer and a drain connecting to a direct current (DC) output terminal. The first, second detecting terminals and feedback terminal are connected with the source, drain and gate of the FET, respectively. Via detecting the current of the DC output terminal, the FET is timely turned on and off to release the energy stored in the transformer.

Current detecting circuit AC/DC flyback switching power supply

A flyback power supply device and its control method that can exactly switch off the switch component each time when the output voltage of the transformer is changed from positive to negative. The power supply device includes a transformer, a primary and secondary switch circuit. The primary and secondary switch circuits are connected with the primary and secondary sides of the transformer, respectively. The secondary switch circuit includes a control circuit and a switch component. The control circuit is used to keep the voltage across the switch component fixed and make the resistance of the switch component inversely proportional to the output current of the transformer. As the output current of the transformer changes as an inverse triangle, the resistance of the switch component will approach infinite when the output current is zero and the switch component will be switched off automatically to make the power supply device function well.

Flyback power supply device and control method thereof

A synchronous control circuit of a flyback switching power supply is connected to a secondary side of a transformer. The synchronous control circuit has several sets of power source ends and a set of induction ends. One output end of the power source ends is connected to a rectifying circuit for rectifying the voltage waveform of the power source ends. The induction ends are connected with a rectifying diode to form a detection end. A synchronous control circuit is connected with the power source ends and the detection end, and has a synchronous input end, a control end, and a waveform adjustment end. The synchronous input end is used for input of a synchronous signal. The control end is connected to the rectifying circuit. The waveform adjustment end is connected to a resistor for controlling the rectifying circuit to generate a uniform rectifying response period.

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Hsin Tien, Taiwan

Hui Chiang Yang