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Part Number HC74HC444

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HD74HC442/HD74HC443/HC74HC444
Quad. Tridirectional Bus Transceiver
(with noninverted 3-state outputs)
Quad. Tridirectional Bus Transceiver
(with inverted 3-state outputs)
Quad Tridirectional Bus Transceiver
(with noninverted/inverted 3-state outputs)
Description
These bus transceivers are designed for a synchronous three-way communication between four-line data
buses. They give the designer a choice of selecting inverting, noninverting or a combination of inverting
and noninverting data paths with 3-state outputs.
The S
0
and S
1
inputs select the bus from which data are to be transferred. The
G inputs enable the bus or
buses to which data are to be transferred. The port for any bus selected for input and any other bus not
enabled for output will be at high impedance.
Features
·
High Speed Operation
·
High Output Current: Fanout of 15 LSTTL Loads
·
Wide Operating Voltage: V
CC
= 2 to 6 V
·
Low Input Current: 1 µA max
·
Low Quiescent Supply Current: I
CC
(static) = 4 µA max (Ta = 25°C)
HD74HC442/HD74HC443HD74HC444
2
Function Table
Inputs
Transfers Between Buses
CS
S
1
S
0
G
A
G
B
G
C
HD74HC442
HD74HC443
HD74HC444
H
X
X
X
X
X
None
None
None
X
H
H
X
X
X
None
None
None
X
X
X
H
H
H
None
None
None
X
L
L
X
H
H
None
None
None
X
L
H
H
X
H
None
None
None
X
H
L
H
H
X
None
None
None
L
L
L
X
L
L
A
B, A
C
A
B,
A
C
A
B,
A
C
L
L
H
L
X
L
B
C, B
A
B
C,
B
A
B
C,
B
A
L
H
L
L
L
X
C
A, C
B
C
A,
C
B
C
A, C
B
L
L
L
X
L
H
A
B
A
B
A
B
L
L
H
H
X
L
B
C
B
C
B
C
L
H
L
L
H
X
C
A
C
A
C
A
L
L
L
X
H
L
A
C
A
C
A
C
L
L
H
L
X
H
B
A
B
A
B
A
L
H
L
H
L
X
C
B
C
B
C
B
HD74HC442/HD74HC443/HD74HC444
3
Pin Arrangement
(Top view)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
CS
B
1
C
1
C
2
B
2
B
3
C
3
C
4
B
4
GND
V
CC
A
1
A
2
A
3
A
4
S
1
S
0
G
C
G
B
G
A
Absolute Maximum Ratings
Item
Symbol
Rating
Unit
Supply voltage range
V
CC
­0.5 to +7.0
V
Input voltage
V
IN
­0.5 to V
CC
+ 0.5
V
Output voltage
V
OUT
­0.5 to V
CC
+ 0.5
V
Output current
I
OUT
±
35
mA
DC current drain per V
CC
GND
I
CC
, I
GND
±
75
mA
DC input diode current
I
IK
±
20
mA
DC output diode current
I
OK
±
20
mA
Power Dissipation per package
P
T
500
mW
Storage temperature
Tstg
­65 to +150
°
C
HD74HC442/HD74HC443HD74HC444
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Logic Diagram
HD74HC442
S
0
A
1
B
1
C
1
A
2
B
2
C
2
A
3
A
4
B
4
C
4
B
3
C
3
S
1
G
A
G
H
G
C
C
S
HD74HC442/HD74HC443/HD74HC444
5
HD74HC443
S
0
A
1
B
1
C
1
A
2
B
2
C
2
A
3
A
4
B
4
C
4
B
3
C
3
S
1
G
A
G
H
G
C
C
S