Datasheet

NE555, NE555Y, SA555, SE555, SE555C
PRECISION TIMERS
SLFS022A – SEPTEMBER 1973 – REVISED SEPTEMBER 2000
14
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
sequential timer
S
V
CC
RESET V
CC
OUT
DISCH
GND
CONT
TRIG
48
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
S closes momentarily at t = 0.
Pin numbers shown are for the D, JG, and P packages.
Figure 22. Sequential Timer Circuit
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.
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
Figure 23. Sequential Timer Waveforms