| 摘要 |
PURPOSE:To obtain a device executed optimizingly when the voltage control with a comparatively light load is conducted systematically by making a voltage impressed to a load variable depending on the switch operation of a current flowing to an input diode of two photocouplers. CONSTITUTION:When a switch section 21 is turned on, an output (TR) of the photocoupler 23 is turned on, and a DC power supply VB obtained from a circuit comprising a diode 17, resistors 14, 26, and a capacitor 25 is set to the collector of the output TR so that an FET12 is turned on completely under the state that the output TR of the coupler 23 is turned on and connected to a gate of an FET12. The relation of VL=VI-(VDB.IL) is obtained and even if the variation of an on-resistance RON exists more or less, the load voltage is stabilized, where VDB is a forward voltage drop of a diode bridge 11, II is the power supply current, IL is a current flowing to a load 4, and RON is the ON-resistance of a power MOSFET. |
