| 摘要 |
PROBLEM TO BE SOLVED: To provide a boosting/dropping power source circuit which is reduced in power loss and improved in efficiency. SOLUTION: A boosting/dropping power source circuit has a first charging circuit 11 composed of a diode 11a and a capacitor 11b provided between the output terminal 19 of the power source circuit and a first or second connecting line J1 or J2. In addition, a first switching transistor 4 is provided in a parallel with a switching transistor 2 for dropping voltage, and the gate of the transistor 4 is connected to the cathode of the diode 11a of the charging circuit 11. A second charging circuit 10 composed of a diode 10a and a capacitor 10b is provided between the input terminal 1 of the power source circuit and the first or second connecting line J1 or J2, a second switching transistor 12 is provided in parallel with a reverse-current preventing diode 13, and the gate of the transistor 12 is connected to the cathode of the diode 10a of the charging circuit 10.
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