| 摘要 |
PURPOSE:To produce a control signal in order to finish an initialization action within a fixed period after application of a power supply and then to start a normal operation after a fixed period of time by a power-on resetting circuit capable of securing a long time of second order. CONSTITUTION:A voltage divider consisting of resistances 9 and 10 and a series circuit of a resistance 11 and a capacitor 12 are connected between a power supply terminal 7 and a ground terminal 8. The joint between the resistance 11 and the capacitor 12 is connected to the input of one side of a voltage level comparator 13; while a voltage division output (f) is supplied to the other input of the comparator 13. The comparator 13 is inverted at a time point when the charging voltage (g) of the capacitor 12 is higher than the output (f) and then inverts an output terminal 14 to a high level from a low level. As the input impedance of the comparator 13 is extremely high, the time constant can be stabilized despite the increment of the level of the resistance 11. Therefore, it is possible to secure easily a period of several seconds with a resistance of several hundreds of KOMEGA and a capacitor of several tens of muF. |
