MC14538 ONSEMI [ON Semiconductor], MC14538 Datasheet - Page 9

• Manufacturer Part Number: MC14538
• Description: Dual Precision Retiggerable/Resettable Monostable Multivibrator
• Manufacturer: ONSEMI [ON Semiconductor]

POWER–DOWN CONSIDERATIONS
large amount of energy stored. When a system containing
the MC14538B is powered down, the capacitor voltage may
discharge from V
at pin 2 or 14. Current through the protection diodes should
be limited to 10 mA and therefore the discharge time of the
V
For example, if V
should discharge no faster than (10 V) x (10 F) / (10 mA)
= 10 ms. This is normally not a problem since power
supplies are heavily filtered and cannot discharge at this rate.
the MC14538B can sustain damage. To avoid this possibility
use an external clamping diode, D
Fig. 11.
DD
Large capacitance values can cause problems due to the
When a more rapid decrease of V
RISING–EDGE
FALLING–EDGE
TRIGGER
TRIGGER
supply must not be faster than (V
A = V
Figure 12. Retriggerable
B = V
Monostables Circuitry
A
B
B
SS
DD
DD
DD
RESET = V
RESET = V
= 10 V and C
through the standard protection diodes
C
C
X
X
DD
DD
R
R
X
X
X
X
= 10 F, the V
, connected as shown in
DD
Figure 14. Connection of Unused Sections
V
V
to zero volts occurs,
DD
DD
DD
Q
Q
Q
Q
). (C) / (10 mA).
V
DD
TYPICAL APPLICATIONS
DD
http://onsemi.com
supply
A
B
MC14538B
9
V
C
DD
D
NC
Q
Q
NC
NC
Figure 11. Use of a Diode to Limit
FALLING–EDGE
RISING–EDGE
TRIGGER
TRIGGER
Power Down Current Surge
V
SS
Figure 13. Non–Retriggerable
C
A
B
A
B
x
Monostables Circuitry
RESET
Q
Q
D
R
RESET = V
x
x
RESET = V
V
V
DD
DD
C
C
X
X
DD
DD
R
R
X
X
Q
V
V
DD
DD
Q
Q
Q