| 摘要 |
PURPOSE:To attain sure operation by detecting a voltage when a power supply voltage is its minimum permissible voltage or below at the rising of the power supply voltage so as to zero the initialized signal voltage and making the rising voltage pass through the permissible voltage lower than the signal voltage. CONSTITUTION:The power supply voltage Vcc is inputted to an inverting input of a comparator 2a and a reference voltage VREF is inputted to a non-inverting input. Further, the power supply voltage Vcc is inputted to an integration circuit having a time constant comprising a resistor R3 and a capacitor C, its output is inputted to an inverting input of a comparator 2b and the power supply voltage Vcc is inputted to a non-inverting input. Then, the comparator 2b detects a delayed voltage and an NOT signal of the output of the comparator 2b is inputted in parallel with the inverting input of the comparator 2b so as to attain initialization. Further, the output of the comparators 2a, 2b is inputted to an NOR circuit, and when a voltage higher than the reference voltage is detected at the rising of the power supply, the initializing signal is transmitted with the time constant of the integration circuit, and when a lower voltage is detected, the initializing signal is cancelled immediately. |
