www.ti.com
SLFS022H – SEPTEMBER 1973 – REVISED JUNE 2010
shows typical waveforms generated during astable operation. The output high-level duration t
H
and
low-level duration t
L
can be calculated as follows:
100 k
t
+
0.693 (R
)
R C
H
A
B)
R
A
+ 2 R
B
= 1 kΩ
t
+
0.693 (R C
R
A
+ 2 R
B
= 10 kΩ
L
B)
Other useful relationships are shown below.
period
+
t
)
t
+
0.693 (R
)
2R ) C
H
L
A
B
1.44
frequency
[
(R
)
2R ) C
A
B
R
L
B
Output driver duty cycle
+
+
t
)
t
R
)
2R
H
L
A
B
Output waveform duty cycle
t
R
H
+
1–
B
+
t
)
t
R
)
2R
H
L
A
B
t
R
B
Low-to-high ratio
+
L
+
t
R
)
R
H
A
B
Figure .
t
f − Free-Running Frequency − Hz
10 k
R
A
+ 2 R
B
= 100 kΩ
1k
100
10
1
R
A
+ 2 R
B
= 1 MΩ
R
A
+ 2 R
B
= 10 MΩ
0.1
0.001
0.01
0.1
1
10
100
C − Capacitance −
µF
Figure 14. Free-Running Frequency
Missing-Pulse Detector
The circuit shown in
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
V
CC
(5 V to 15 V)
Input
2
4
RESET
TRIG
8
V
CC
OUT
R
L
3
DISCH
5
0.01
µ
F
CONT
GND
1
7
THRES
6
A5T3644
Pin numbers shown are shown for the D, JG, P, PS, and PW packages.
Figure 15. Circuit for Missing-Pulse Detector
Copyright © 1973–2010, Texas Instruments Incorporated
Product Folder Link(s):
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎ
ÎÎÎÎÎ ÎÎÎ
ÎÎÎÎÎ ÎÎÎ
ÎÎÎÎÎ ÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
R
A
V
CC
= 5 V
R
A
= 1 kΩ
C = 0.1
µF
See Figure 15
Voltage − 2 V/div
Output
Input Voltage
C
Output Voltage
Capacitor Voltage
Time − 0.1 ms/div
Figure 16. Completed Timing Waveforms for
Missing-Pulse Detector
11
TI [ TEXAS INSTRUMENTS ]
