| 摘要 |
PURPOSE:To prevent malfunctions of the system caused by surge pulses, by maintaining an H-level output for a fixed time from the rise of the clock pulse. CONSTITUTION:A surge pulse PN1 mixed under an H-level condition of a clock pulse alpha acts to switch the charging of a condenser C1 to the discharging, but, since the time is short, the voltage at a connecting point (b) is higher than a threshold voltage Vth and, because the feedback input of an OR gate 8 is maintained at an H level, the surge pulse PN1 does not appear in an output (c). When a surge pulse PN3 is mixed during a quiescent period in which the output of the OR gate 8 is fallen to an L level, a noise, in which the surge pulse PN3 is clipped to the output of the OR gate 8 at the H level, is generated, and the output of an OR gate 3 is brought up to the H level through the condenser C1 and a resistance R3. However, since the rise by the surge pulse PN3 is connected to the next clock pulse, influences by the surge pulse can be ignored practically. |
