| 摘要 |
PURPOSE:To reduce the power loss of a switching regulator by providing an auxiliary power source for a switching element drive circuit and using the auxiliary power source after starting, thereby increasing the drive capacity. CONSTITUTION:A drive circuit is started by the voltage from a power source for the drive circuit, which is reduced via a resistor 2 from the voltage of a conventional power source 1 when the power source is energized. After starting, the AC voltage which is generated at the additional coil is rectified and smoothed via a diode 21 and a condenser 22, the DC voltage is supplied through a diode 25 and a resistor 24 to the auxiliary power source, the base bias current of a transistor 8 is increased by a resistor 23 to increase the drive capacity of the drive circuit. In this manner, the capacity of the auxiliary power source circuit which has the resistor 2 and a Zener diode 3 can be reduced to a small value which can energize the power source, and the capacity of the drive circuit can be reduced by increasing a resistor 6. |
