| 摘要 |
PROBLEM TO BE SOLVED: To provide a step-down type DC-DC converter which is resistant to common mode noise and can make low DC output voltage from high DC input voltage without being subjected to serious restriction, concerning a used main transistor, its drive circuit, and the on/off frequency of the main transistor. SOLUTION: This converter is provided with a diode 9 whose anode terminal is connected to the junction between an inductance element 4 and the positive electrode of a capacitor 5 and whose cathode terminal is connected to the junction between a resistor 12 and the positive electrode of a capacitor 8, and the source terminal of a MOSFET 2 is made the ground of a control circuit 7. Hereupon, the power supply to a power source for drive of the control circuit 7 is performed through the diode 9 from the output side of the step-down type DC-DC converter, utilizing that the source terminal voltage of the MOS-FET 2 becomes lower than the potential on output side of the step-down type DC-DC converter when the MOS-FET 2 is off. |
