| 摘要 |
PURPOSE:To obtain a simple circuit that does not require special operation when making or breaking power supply by comparing power supply input with the reference voltage using a comparator which is operated by charging voltage of a condenser and making the output a power supply decision signal. CONSTITUTION:Power supply input is compared with the reference voltage of a comparator 24 which is operated by charging voltage Vc of a condenser 23 charged from power supply input of a logical circuit through a reverse current checking circuit, and the output is made a power supply decision signal. For instance, the condenser 23 is charged by input voltage Vi through a diode 22, and the charging voltage Vc is supplied to the comparator 24 to make it power supply for operation of the comparator 24. The input voltage Vi is voltage divided by resistances 20, 21 and the divided voltage Vx is inputted to the comparator 24. The voltage Vx is compared with the reference voltage, and while input voltage Vi is lower than detected voltage VD, output line 13 of the comparator 24 is made high impedance (off). |
