RECTIFICATION SWITCHING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a reliable rectification switching circuit which does not use gate elements or triacs as switch elements, is highly efficient due to remarkable reduction of driving power and reduction of loss at energization, and is free from a possibility that the rectification mode is repeated in proximity to the threshold of input voltage at which the rectification mode is switched. SOLUTION: The rectification switching circuit detects alternating-current input voltage through a control circuit. According to its switching signal, the switching circuit switches between voltage doubler rectification mode for 100V AC and bridge rectification mode for 200V AC through switch elements so that the direct-current output voltage will be substantially identical. The rectification switching circuit uses field-effect transistors whose sources are connected in common as the switch elements. The common source of the field-effect transistors is connected with the zero volt line of the control circuit so that the field-effect transistors can be directly driven. The control circuit is provided with a hysteresis so that the input voltage at switching of the rectification mode and that at canceling are different from each other. COPYRIGHT: (C)2004,JPO&NCIPI