| 摘要 |
PURPOSE:To stabilize the output voltage of a switching regulator by providing a variable switching circuit for blocking part of the output supplied to a load during the conduction period of a primary side switch element at the secondary side of a transformer. CONSTITUTION:A power supply circuit is composed of a DC power source 1, a transformer 2 having a primary winding NP, a secondary winding NS, and a switch element driving winding NG, and a primary side switch element 3 opened or closed in a predetermined conduction width by a predetermined synchronization. Secondary side switch elements 4, 5, and an AND circuit 6 for comparing a voltage from the output side of a choke coil 8 with a preset reference voltage to produce a logic product of the comparison output and the output from the winding NG for controlling the elements 4, 5 by the output are provided, and a variable switch circuit 7 for blocking part of a load side supplying output during the conduction period of the element 3 is formed. Thus, the output voltage can be stabilized without feeding back a monitor signal of the secondary output to the primary side.
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