| 摘要 |
<p>PURPOSE:To make it possible to make the response speed higher and lower for high-frequency noise, etc., and an input break time respectively by taking OR between the output of a high-response speed detection means and the output of a low-response speed detection means as a low voltage detection output. CONSTITUTION:OR gate 11 is proviede which operates OR between the output of voltage comparator 6 (comparison voltage VTH1) and the output of voltage comparator 10 (comparison voltage VTH2, VTH1>VTH2). In respect to the response for the noise voltage at time t1, if VTH2 is set lower than the voltage drop dependent upon allowable noise, comparators 6 and 10 are not operated to output no low voltage detection output. Next, at time t2, though comparator 6 is operated at response time Td2,comparator 10 is operated immediately when the input voltage becomes below VTH2 because the input voltage passes through no integrating circuit, and the output of rapider one of voltage comparators is transmitted to power source 7 and unit 8 by gate 11. That is, the circuit does not cause malfunction at the allowable voltage drop by noise by setting VTH1>VTH2, and an extreme voltage drop can be detected surely even if this voltage drop is temporary.</p> |
