| 摘要 |
PURPOSE:To secure protection by amplifying the difference between a set overcurrent detection level and a detection voltage, and turning off a main control element and also supplying it to the output voltage size of a constant voltage circuit. CONSTITUTION:The constant voltage circuit consists of a transistor Tr3 as a main control element, resistance 2, and Zener diode 4, and its output voltage V0 is applied to a load 12 through a resistance 11 for current detection and also applied to an amplifying circuit 7 through level setting circuits 8 and 9 to turn off the Tr3 through the Tr5 when an overcurrent is detected. In this case, the output of amplifying circuit 7 and the output of the constant voltage circuit are connected together through the series circuit of a resistance 13 and a diode 14. Consequently, even when the Tr3 turns off completely, the voltage of the amplifying circuit 7 is supplied to its output side to maintain the voltage necessary for bridge circuits 8-12 for overcurrent detection. |
