| 摘要 |
PURPOSE:To detect exactly low voltage abnormality of a power supply voltage, too, by converting the output of a comparator for detecting the highest detecting voltage or above and the lowest detecting voltage or below, to a logical value signal of normality and abnormality by using a photocoupler. CONSTITUTION:In case a power source to be measured which is applied to two signal lines if ''0''V or abnormally low, a current flowing through a diode in a photocoupler 16 is ''0'' or about ''0''. When a power supply voltage is the lowest detecting voltage or below, an output of a comparator 15 becomes on, and in the same way, a photodiode current is ''0''. Also, when said voltage is the lowest detecting voltage or above, and the highest detecting voltage or below, an output of a comparator 13 becomes on, and both outputs of comparators 14, 15 become off, therefore, the photodiode current flows. When said voltage is the highest detecting voltage or above, the output of the comparator 14 becomes on, the photodiode current does not flow, and normality/abnormality of the power supply voltage can be known by a logical value of ''1'' and ''0''.
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