Kawasaki Microelectronics, Inc.

Ichiro Tamaki

A switching-type power-supply which enables the switching with little power loss and a method of switching the switching-type power-supply are provided. The switching-type power-supply unit includes a transformer with primary, secondary, winding and control windings, a switch which switches supply of a primary current from a dotted terminal to a non-dotted terminal through the primary winding, a rectifying diode connected the secondary winding, a monitoring signal generation circuit with a diode and a resistor, the diode between GND and a dotted terminal of the control winding, the resistor between GND and a non-dotted terminal of the control winding, the monitoring signal generation circuit generating a monitoring signal at the dotted terminal of the control winding, and a control unit with a zero-point detector and a controller. The zero-point detector monitoring the monitoring signal and supplying a detection signal to the controller. The controller determining on-timing of the switch based on the detection signal supplied from the zero-point detector.

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Mihama-ku, Japan

Ichiro Tamaki