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PRECISION TIMERS
SLFS022F – SEPTEMBER 1973 – REVISED JUNE 2006
APPLICATION INFORMATION (continued)
Sequential Timer
Many applications, such as computers, require signals for initializing conditions during start-up. Other
applications, such as test equipment, require activation of test signals in sequence. These timing circuits can be
connected to provide such sequential control. The timers can be used in various combinations of astable or
monostable circuit connections, with or without modulation, for extremely flexible waveform control.
shows a sequencer circuit with possible applications in many systems, and
shows the output
waveforms.
V
CC
4
RESET
2
S
5
CONT
TRIG
8
V
CC
3
OUT
DISCH
7
6
RA 33 kΩ
2
0.001
µF
5
4
RESET
TRIG
8
V
CC
3
OUT
DISCH 7
R
B
33 kΩ
2
0.001
µF
5
4
RESET
TRIG
8
V
CC
3
OUT
DISCH
7
6
R
C
0.01
µF
THRES
GND
1
C
A
CONT
0.01
µF
Output A
THRES
GND
1
C
B
6
CONT
0.01
µF
THRES
GND
1
C
C
C
A
= 10 µF
R
A
= 100 kΩ
C
B
= 4.7 µF
R
B
= 100 kΩ
Output B
C
C
= 14.7 µF
R
C
= 100 kΩ
Output C
Pin numbers shown are for the D, JG, P, PS, and PW packages.
NOTE A: S closes momentarily at t = 0.
Figure 22. Sequential Timer Circuit
Output A
t
w
A
Output B
Output C
Figure 23. Sequential Timer Waveforms
ÏÏÏ
ÏÏÏ
ÏÏÏ
ÏÏÏ
ÏÏÏÏÏ ÏÏ
ÏÏÏÏÏ ÏÏ
ÏÏÏÏÏ ÏÏ
ÏÏÏ
ÏÏÏÏÏ
ÏÏÏ
ÏÏÏÏÏ
ÏÏÏ
ÏÏÏ
ÏÏÏÏ
ÏÏÏÏÏ
ÏÏÏÏ
ÏÏ
ÏÏÏÏÏ
t
w
A = 1.1 R
A
C
A
t
w
B
t
w
B = 1.1 R
B
C
B
t
w
C
t
w
C = 1.1 R
C
C
C
t=0
t − Time − 1 s/div
ÏÏÏÏ
ÏÏÏÏ
ÏÏÏÏ
ÏÏÏÏ
ÏÏÏÏ
ÏÏÏÏ
ÏÏÏÏÏÏ
Ï
ÏÏÏÏÏÏ
Ï
ÏÏÏ
ÏÏÏÏÏÏ
Ï
ÏÏÏÏÏ
ÏÏÏÏÏÏ
ÏÏÏ
ÏÏÏÏÏ
See Figure 22
Voltage − 5 V/div
15
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