Diodes NA555 - Manual (Page 9)

NE555/SA555/NA555
PRECISION TIMERS
NE555/SA555/NA555
Document number: DS35112 Rev. 4 - 2
9 of 14
www.diodes.com
February 2012
© Diodes Incorporated
NEW PROD
UC
T
Typical Applications Characteristics (cont.)
Missing Pulse Detector
The circuit shown in Figure 7 can be used to detect a missing pulse or abnormally long spacing between consecutive pulses
in a train of pulses. The timing interval of the monostable circuit is retriggered continuously by the input pulse train as long as
the pulse spacing is less than the timing interval. A longer pulse spacing, missing pulse, or terminated pulse train permits the
timing interval to be completed, thereby generating an output pulse as shown in Figure 8.
Fig. 7 Circuit for Missing Pulse Dectector Fig. 8 Timing Waveforms for Missing Pulse
Dectector
Frequency Divider
By adjusting the length of the timing cycle, the basic circuit of Figure 1 can be made to operate as a frequency divider. Figure
9 shows a divide-by-three circuit that makes use of the fact that retriggering cannot occur during the timing cycle.
Fig. 9 Divide by Three Circuit Waveforms