TLC555-Q1 Datasheet, PDF (17/25 Pages) Texas Instruments – LinCMOS™ TIMER

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TLC555-Q1
SLFS078B – OCTOBER 2006 – REVISED OCTOBER 2015
Typical Applications (continued)
9.2.4 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. Figure 18
shows a sequencer circuit with possible applications in many systems, and Figure 19 shows the output
waveforms.
V_DD
4
8
RA 33 kW
4
8
R_B 33 kW
4
8
R_C
RESET
2
TRIG
V_DD
OUT
3
RESET
2
TRIG
V_DD
OUT
3
RESET
2
TRIG
V_DD
OUT
3
0.001
0.001
S
DISCH ⁷
mF
DISCH ⁷
mF
7
DISCH
5
CONT
THRES ⁶
5
CONT
6
THRES
5
CONT
THRES ⁶
GND
GND
GND
0.01
mF
1
C_A
0.01
mF
1
C_B
0.01
mF
1
C_C
C_A = 10 mF
R_A = 100 kW
Output A
NOTE A: S closes momentarily at t = 0.
C_B = 4.7 mF
R_B = 100 kW
Output B
C_C = 14.7 mF
R_C = 100 kW
Output C
Figure 18. Sequential Timer Circuit
9.2.4.1 Design Requirements
The sequential timer application chains together multiple mono-stable timers. The joining components are the 33-
kΩ resistors and 0.001-µF capacitors. The output high to low edge passes a 10-µs start pulse to the next
monostable.
9.2.4.2 Detailed Design Procedure
The timing resistors and capacitors can be chosen using this formula. t_w = 1.1 × R × C.
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