TS556_08 STMICROELECTRONICS [STMicroelectronics], TS556_08 Datasheet - Page 13

• Manufacturer Part Number: TS556_08
• Description: Low-power dual CMOS timer
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TS556
4.2
Astable operation
When the circuit is connected as shown in
and runs as a multivibrator. The external capacitor charges through R
discharges through R
two resistors.
In the astable mode of operation, C charges and discharges between 1/3 V
As in the triggered mode, the charge and discharge times and therefore frequency, are
independent of the supply voltage.
Figure 6.
Figure 7
The charge time (output HIGH) is given by:
and the discharge time (output LOW) by:
Thus the total period T is given by:
The frequency of oscillation is then:
The duty cycle is given by:
Figure 7.
shows actual waveforms generated in this mode of operation.
t1 = 0.693 (R
t2 = 0.693 x R
T = t1 + t2 = 0.693 (R
Application schematic
Timing diagram
B
A
only. Thus the duty cycle may be precisely set by the ratio of these
B
+ R
D =
f =
x C
B
) C
1
-- - =
T
---------------------------
RA
Voltage
0.01 F
Control
A
V
RB
μ
------------------------------------- -
(RA
+ 2R
+
CC
Out
R = R = 4.8 k , C = 0.1 F , R = 1.0k
2RB
A
t = 0.5 ms / div
OUTPUT VOLTAGE = 5.0V/div
CAPACITOR VOLTAGE = 1.0V/div
+
1.44
B
B
2RB )C
) C
Reset
Figure 6
Ω
TS556
1/2
μ
(pins 2 and 6 connected) it triggers itself
L
Ω
R
R
C
B
A
Application information
A
and R
CC
B
and 2/3 V
and
13/19
CC
.