74vhc123a Fairchild Semiconductor, 74vhc123a Datasheet - Page 3

• Manufacturer Part Number: 74vhc123a
• Description: Dual Retriggerable Monostable Multivibrator
• Manufacturer: Fairchild Semiconductor

©1993 Fairchild Semiconductor Corporation
74VHC123A Rev. 1.2
Block Diagrams
Note A: C
Note B: External clamping diode, D
External capacitor is charged to V
If the supply voltage is turned off, C
and V
capacitance of the supply voltage filter is large enough and V
limited and damage to the IC is avoided.
The maximum value of forward current through the parasitic diode is ±20mA. In the case of a large Cx, the limit of fall
time of the supply voltage is determined as follows:
t
(t
In the event a system does not satisfy the above condition, an external clamping diode (D
from rush current.
f
f
≥ (V
is the time between the supply voltage turn off and the supply voltage reaching 0.4 V
CC
CC
–0.7) C
drops rapidly, there will be some possibility of damaging the IC through in rush current or latch-up. If the
x
, R
x
, D
x
x
/ 20mA
are external Capacitor, Resistor, and Diode, respectively.
CC
x
x
;
discharges mainly through the internal (parasitic) diode. If C
level in the wait state, i.e. when no trigger is applied.
3
CC
drops slowly, the in rush current is automatically
CC
x
) is needed to protect the IC
)
x
is sufficiently large
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