HD74HC4538
Dual Precision Retriggerable/Resettable Monostable
Multivibrators
Description
Each multivibrator features both a negative, A, and a positive, B, transition triggered input, either of which
can be used as an inhibit input. Also included is a clear input that when taken low resets the one short. The
HD74HC4538 is retriggerable. That is, it may be triggered repeatedly while their outputs are generating a
pulse and the pulse will be extended.
Pulse width stability over a wide range of temperature. The output pulse equation is simply: t
w
= 0.7 (R)
(C).
Features
High Speed Operation: t
pd
(A or B to Y) = 22 ns typ (C
L
= 50 pF)
High Output Current: Fanout of 10 LSTTL Loads
Wide Operating Voltage: V
CC
= 2 to 6 V
Low Input Current: 1 A max
Low Quiescent Supply Current
Function Table
Inputs
Outputs
C
D
A
B
Q
Q
L
X
X
L
H
H
L
H
H
H
H
Not triggered
H
L
Not triggered
X :
Irrelevant
HD74HC4538
4
Absolute Maximum Ratings
Item
Symbol
Rating
Unit
Supply voltage range
V
CC
0.5 to +7.0
V
Input voltage
Vin
0.5 to V
CC
+ 0.5
V
Output voltage
Vout
0.5 to V
CC
+ 0.5
V
DC input diode current
I
IK
20
mA
DC input diode current pin 2, 14
I
IK
30
mA
DC output diode current
I
OK
20
mA
DC current drain per pin
Iout
25
mA
DC current drain per V
CC
, GND
I
CC
, I
GND
50
mA
Power dissipation per package
P
T
500
mW
Storage temperature
Tstg
65 to +150
C
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