TLC555-Q1 Datasheet, PDF (11/25 Pages) Texas Instruments – LinCMOS™ TIMER

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Feature Description (continued)
100 k
10 k
1k
TLC555-Q1
SLFS078B – OCTOBER 2006 – REVISED OCTOBER 2015
R_A + 2 R_B = 1 kW
R_A + 2 R_B = 10 kW
R_A + 2 R_B = 100 kW
100
10
1
R_A + 2 R_B = 1 MW
R_A + 2 R_B = 10 MW
0.1
0.001
0.01
0.1
1
10
100
C − Capacitance − mF
Figure 9. Free-Running Frequency
8.3.3 Frequency Divider
By adjusting the length of the timing cycle, the basic circuit of Figure 11 can be made to operate as a frequency
divider. Figure 10 shows a divide-by-three circuit that makes use of the fact that re-triggering cannot occur during
the timing cycle.
V_CC = 5 V
R_A = 1250 W
C = 0.02 mF
See Figure 9
Input Voltage
Output Voltage
Capacitor Voltage
Time − 0.1 ms/div
Figure 10. Divide-by-Three Circuit Waveforms
8.4 Device Functional Modes
Table 1 shows the device functional modes.
RESET
Low
High
High
High
TRIGGER VOLTAGE⁽¹⁾
Irrelevant
<1/3 V_CC
>1/3 V_CC
>1/3 V_CC
(1) Voltage levels shown are nominal.
Table 1. Function Table
THRESHOLD VOLTAGE⁽¹⁾
Irrelevant
Irrelevant
>2/3 V_CC
<2/3 V_CC
OUTPUT
DISCHARGE SWITCH
Low
On
High
Off
Low
On
As previously established
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