| 摘要 |
PURPOSE:To prevent reckless driving and erroneous operation and to enhance reliability and safety, by using the output signal of a power breakdown detecting circuit as the auto-reset pulse for an operation circuit in the DC constant voltage side for the operation circuit to positively perform initial reset at the time of the restoration of power breakdown. CONSTITUTION:When a power source switch 2 is closed and current voltage Vcc rises, the output point A of a comparator 10 for detecting power breakdown comes to an H-level in a state lower than reference voltage Vref and comes to an L-level in a state higher than said reference voltage Vref. In such a I OFF state that the time of power breakdown is long, when the power breakdown is restored, a point B is raised as Vcc rises but, when becomes higher than the threshold voltage of a wave form shaping circuit 8, it comes to L and, when becomes higher than Vref, it comes to H. This L-pulse is a reset pulse. With respect to short time power breakdown as shown in a II OFF state, there exists no problem. In a III OFF state, the perfect L-pulse is obtained at the point B and an operation circuit 9 is normally subjected to initial reset. |
