| 摘要 |
PURPOSE:To eliminate power consumption in a bias means by inserting a bias control means into feeder line of means for biasing an electronic switch thereby interrupting power supply to the bias means upon turn OFF of the electronic switch. CONSTITUTION:When load current from an output terminal OUT increases, voltage across a resistor Rs for detecting the load current also increases. When the voltage exceeds the ON voltage of a transistor Q2, the transistor Q2 is turned ON. Consequently, a current flows into a LED 12 in a photocoupler U1 and light is emitted therefrom thus turning a switch 10 on the light receiving side of the photocoupler U1 ON. Since the base and the emitter of a transistor Q3 are short-circuited through switching of the photocoupler U1, the transistor Q3 is turned OFF. Consequently, base bias of the transistor Q1 is interrupted and the transistor Q1 is also turned OFF. |
