| 摘要 |
PROBLEM TO BE SOLVED: To obtain a stable output regardless of fluctuation in power supply voltage, and ensure reliability of an element. SOLUTION: In this DC-DC converter, a primary coil current of a step-up transformer 1 supplied from a power supply device is intermitted by a power MOS-FET 2, and charging of a capacitor for ignition is performed through a rectifier diode by a secondary coil voltage of the step-up transformer 1 boosted by a flyback voltage of a coil. The DC-DC converter comprises: a current detection circuit 5 for detecting a drain current of the power MOS-FET 2; and control circuits (6, 7) which turn OFF the power MOS-FET 2 at a predetermined period of time and thereafter turn ON again the power MOS-FET 2 when the drain current detected by the current detection circuit 5 exceeds a predetermined threshold. COPYRIGHT: (C)2004,JPO
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