TS555C STMicroelectronics, TS555C Datasheet - Page 9

• Manufacturer Part Number: TS555C
• Description: LOW POWER SINGLE CMOS TIMERS
• Manufacturer: STMicroelectronics

ASTABLE OPERATION
When the circuit is connected as shown in figure 4
(pin 2 and 6 connected) it triggers itself and free
runs as a multivibrator. The external capacitor
charges through R
through R
cisely set by the ratio of these two resistors.
In the astable mode of operation, C charges and
discharges between 1/3 V
triggered mode, the charge and discharge times
and therefore frequency, are independent of the
supply voltage.
Figure 5 shows actual waveforms generated in this
Figure 4
Voltage
0.01 F
Control
V
CC
Out
B
only. Thus the duty cycle may be pre-
5
Reset
3
1
A
4
TS555
a n d R
CC
and 2/3 V
B
8
2
and discharges
7
6
CC
. As in the
R
R
C
B
A
mode of operation.
The charge time (output HIGH) is given by :
t1 = 0.693 (R
and the discharge time (output LOW) by :
t2 = 0.693 (R
Thus the total period T is given by :
T = t1 + t2 = 0.693 (R
The frequency of oscillation is then :
f
The duty cycle is given by : D
Figure 5
T
1
R = R = 4.8 k , C = 0.1 F , R = 1.0k
A
R
t = 0.5 ms / div
OUTPUT VOLTAGE = 5.0V/div
CAPACITOR VOLTAGE = 1.0V/div
A
1.44
B
A
B
2
) C
+ R
R
B
B
C
) C
A
+ 2R
B
) C
R
A
R
L
TS555C,I,M
B
2
R
B
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