| 摘要 |
<p>PURPOSE:To prevent a false operation of a circuit and to improve precision by making each of positive and negative terminals of an overcurrent detecting comparator have a time constant each time of turning ON and OFF of a power source of an apparatus. CONSTITUTION:This circuit shuts down a power circuit by an output of an overcurrent detecting comparator 13 which conducts and OFF operation in the state of a normal operation and an ON operation at the time of an overcurrent. By providing a time constant resistor 6 and a time constant capacitor 7 as a time constant circuit, on the occasion, the rise of a positive input terminal (a) of the comparator 13 is delayed when the power source of the apparatus turns ON, and thereby a false output thereof is prevented. Besides, a time constant capacitor 11 is provided as the time constant circuit and made to have a time constant, together with an overcurrent detecting split resistor 9, and thereby the fall of a negative input terminal (b) of the comparator 13 is delayed when the power source of the apparatus turns OFF. By setting values of overcurrent detecting split resistors 9 and 10 to be larger enough than values of overcurrent detecting reference split resistors 3 and 4, a discharge time constant of the fall of the terminal (b) is made larger than the one of the terminal (a).</p> |
