| 摘要 |
PURPOSE:To detect the voltage at the time of starting with high accuracy by providing a substantial hysteresis characteristic to the input and output transmission characteristics of a second comparator. CONSTITUTION:Lower reference voltage VL is supplied to the base of one differential transistor Q1 and a voltage signal Vin is supplied to the base of the other differential transistor Q2 while higher reference voltage VH is supplied to the base of one differential transistor Q6 and the voltage signal Vin is directly supplied to the base of the other differential transistor Q5. A window comparator is constituted of two transistors Q1, Q2 and two transistors Q5, Q6 and, when the voltage signal Vin to be mentioned is between the reference voltages VL, VH, the output signal corresponding thereto is formed. Then, by providing a substantial hysteresis characteristic to the input and output characteristics of the second comparator and allowing the voltage Vin to be monitored at the time of starting to reach the reference voltage VH, the voltage Vin can be equivalently highly set by the offset voltage in the hysteresis characteristic. |
