NE555, SA555, SE555, SE555C
PRECISION TIMERS
SLFS022 – D1669, SEPTEMBER 1973—REVISED FEBRUARY 1992
APPLICATION INFORMATION
sequential timer
VCC
4
RESET
2
S
5
CONT
TRIG
8
VCC
OUT
DISCH
RA 33 kΩ
3
7
6
0.01
µF
0.001
µF
5
2
4
RESET
TRIG
8
VCC
OUT
3
RB
33 kΩ
2
0.001
µF
5
4
RESET
TRIG
8
VCC
OUT
DISCH
3
7
6
RC
DISCH 7
CONT
THRES
GND
1
CB
6
0.01
µF
THRES
GND
1
CONT
THRES
GND
1
CA
0.01
µF
CC
CA = 10
µF
RA = 100 kΩ
Output A
S closes momentarily at t = 0.
Pin numbers shown are for the D, JG, and P packages only.
CB = 4.7
µF
RB = 100 kΩ
Output B
CC = 14.7
µF
RC = 100 kΩ
Output C
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 may
be connected to provide such sequential control. The timers may be used in various combinations of astable
or monostable circuit connections, with or without modulation, for extremely flexible waveform control. Figure 22
illustrates a sequencer circuit with possible applications in many systems, and Figure 23 shows the output
waveforms.
See Figure 22
Output A
twA
Output B
Figure 23. Sequential Timer Waveforms
14
POST OFFICE BOX 655303
ÏÏ
ÏÏÏÏ
Output C
t=0
t – Time – 1 s/div
ÏÏÏÏÏ
ÏÏÏÏÏÏÏÏ
ÏÏÏÏ
ÏÏÏ
Ï
ÏÏ
ÏÏÏÏÏ
ÏÏÏÏÏ
twA = 1.1 RACA
twB
twB = 1.1 RBCB
twC
twC = 1.1 RCCC
ÏÏÏÏ
ÏÏÏÏ
ÏÏ
ÏÏÏÏÏ
Ï
ÏÏÏÏÏ
Voltage – 5 V/div
•
DALLAS, TEXAS 75265
TI [ TEXAS INSTRUMENTS ]
