MC3456P ON Semiconductor, MC3456P Datasheet - Page 8

• Manufacturer Part Number: MC3456P
• Manufacturer: ON Semiconductor

Specifications of MC3456P

• Lead Free Status / Rohs Status: Not Compliant

Astable Mode
retrigger itself and cause the capacitor voltage to oscillate
between 1/3 V
R
ratio of these resistors the duty cycle can be varied. The
charge and discharge times are independent of the supply
voltage.
The charge time (output high) is given by:
The discharge time (output low) by:
Thus the total period is given by:
and may be easily found as shown in Figure 19.
The duty cycle is given by:
To obtain the maximum duty cycle, R
possible; but it must also be large enough to limit the
The frequency of oscillation is then:
B
In the astable mode the timer is connected so that it will
The external capacitor charges to 2/3 V
and discharges to 1/3 V
T = t
CC
and 2/3 V
1
t
1
+ t
t
= 0.695 (R
2
2
= 0.695 (R
= 0.695 (R
CC
CC
DC =
through R
(see Figure 17).
A
+R
B
A
) C
R
B
+ 2R
) C
A
f =
R
A
B
+2R
must be as small as
CC
1
T
B
B
) C
. By varying the
=
B
through R
(R
A
1.44
+2R
http://onsemi.com
A
B
and
) C
8
discharge current (Pin 7 current) within the maximum rating
of the discharge transistor (200 mA).
The minimum value of R
0.001
0.01
100
1.0
0.1
10
0.1
(R
R
A
Figure 19. Free Running Frequency
A
+ 2 R
1.0
≥
f, FREE RUNNING FREQUENCY (Hz)
B
)
V
CC
I
7
10
(A)
(Vdc)
A
is given by:
≥
100
V
CC
0.2
1.0 k
(Vdc)
10 k
100