Datasheet
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Sequential Timer
S
V
CC
RESET V
CC
OUT
DISCH
GND
CONT
TRIG
4 8
3
7
6
1
5
2
THRES
R
C
C
C
0.01
C
C
= 14.7 µF
R
C
= 100 kΩ
Output C
RESET V
CC
OUT
DISCH
GND
CONT
TRIG
4 8
3
7
6
1
5
2
THRES
R
B
33 kΩ
0.001
0.01
µF
C
B
= 4.7 µF
R
B
= 100 kΩ
Output BOutput A
R
A
= 100 kΩ
C
A
= 10 µF
µF
0.01
µF
0.001
33 kΩ
RA
THRES
2
5
1
6
7
3
84
TRIG
CONT
GND
DISCH
OUT
V
CC
RESET
µF
µF
C
B
C
A
Pin numbers shown are for the D, JG, P, PS, and PW packages.
NOTE A: S closes momentarily at t = 0.
Voltage − 5 V/div
t − Time − 1 s/div
See Figure 22
Output A
Output B
Output C
t = 0
t
w
C = 1.1 R
C
C
C
t
w
C
t
w
B = 1.1 R
B
C
B
t
w
A = 1.1 R
A
C
A
t
w
A
t
w
B
NA555 , NE555 , SA555 , SE555
PRECISION TIMERS
SLFS022F – SEPTEMBER 1973 – REVISED JUNE 2006
APPLICATION INFORMATION (continued)
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. Figure 22
shows a sequencer circuit with possible applications in many systems, and Figure 23 shows the output
waveforms.
Figure 22. Sequential Timer Circuit
Figure 23. Sequential Timer Waveforms
15
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