| 摘要 |
PROBLEM TO BE SOLVED: To provide a step-down converter with a boosting function capable of reducing the cost and size by decreasing the number of components and the labor. SOLUTION: The step-down converter with the boosting function comprises a switching element Q2 and a diode D2 connected in series between input terminals (T1 and T2) applied by a DC input voltage, a choke coil L1 and a capacitor C1 connected in series between terminals of the diode D2, and a circuit 1 for controlling the DC output voltage obtained from between terminals of the capacitor C1 by driving the element Q2 on/off in high frequency. When the element Q2 is turned off, an input energy stored in the coil L1 during an on period of the element Q2 is discharged to flow to the capacitor C1 through the diode D2, thereby obtaining an output voltage stepped down from between the terminals of the capacitor C1. A sub-winding L1' is provided in the coil L1. Thus, a boosting DC voltage obtained by smoothing an induced voltage of the winding L1' obtained based on the input energy of the coil L1 is superposed on the input voltage.
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