| 摘要 |
<p>A power circuit including an input circuit for receiving an AC power supply voltage from an AC power line, a primary circuit rectifier coupled to the input circuit for rectifying the AC power supply voltage, a transformer having a primary winding, a secondary winding and a tertiary winding, DC coupling member for coupling an output terminal of the primary circuit rectifier to one end of the primary winding of the transformer, a secondary circuit rectifier for rectifying a secondary circuit AC voltage induced across the secondary winding of the transformer to output a DC voltage resulted by its rectification from the power circuit, a switching element coupled to the other end of the primary winding of the transformer, a controller for controlling the duty ratio of the ON/OFF operations of the switching element so as that the output DC voltage from the secondary circuit rectifier is regulated, and a switched frequency AC signal generator, including the tertiary winding of which one end is coupled to one end side of the primary winding of the transformer and a first smoothing capacitor coupled between the other end of the tertiary winding and a reference potential line, for generating an AC signal responsive to the duty ratio of the ON/OFF operation of the switching element across the tertiary winding. <IMAGE></p> |
