| 摘要 |
PURPOSE:To reduce the effect of a clamp voltage at power supply interruption, by adding a constant voltage diode and a resistor to a conventional circuit and utilizing the reverse characteristic of the constant voltage diode. CONSTITUTION:The relation V1=IR5+V(I) is obtained, where I is current flowing to the constant voltage diode D and V(I) is a voltage across the diode. When the voltage V1 is within the region ''a'' of the characteristic diagram of the diode, since the relation, operating voltage of diode D>resistor R5 exists, a voltage V0' at a point B is regarded as V0' 0. When the voltage V1 enters the region ''c'' with the application of power supply, a capacitor C2 is charged with the time constant comprising a resistor R3 and the capacitor C2, and the potential V0'' at the point B reaches V0''(=V1-V(1)), where I (V1-V2)/R5 and V2 is the Zener voltage of the diode. Thus, in selecting the circuit components so that the potential V0' is smaller than the input ''O'' level guarantee voltage of the logic elements and V0'' exceeds the input ''1'' level guarantee voltage of the logic elements, the clamp voltage is neglected even if the power supply is clamped up to a voltage Vcc giving the maximum value of the potential V0'. |
