HD74AC139/HD74ACT139
Dual 1-of-4 Decoder/Demultiplexer
Description
The HD74AC139/HD74ACT139 is a high-speed, dual 1-of-4 decoder/demultiplexer. The device has two
independent decoders, each accepting two inputs and providing four mutually-exclusive active-Low
outputs. Each decoder has an active-Low Enable input which can be used as a data input for a 4-output
demultiplexer. Each half of the HD74AC139/HD74ACT139 can be used as a function generator providing
all four minterms of two variables.
Features
·
Multifunction Capability
·
Two Completely Independent 1-of-4 Decoders
·
Active Low Mutually Exclusive Outputs
·
Outputs Source/Sink 24 mA
·
HD74ACT139 has TTL-Compatible Inputs
HD74AC139/HD74ACT139
2
Pin Arrangement
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
E
a
A
0a
A
1a
O
0a
O
1a
O
3a
O
2a
GND
V
CC
E
b
A
0b
A
1b
O
0b
O
1b
O
2b
O
3b
(Top view)
Logic Symbol
DECODER a
O
0
A
0
E
A
1
O
1
O
2
O
3
DECODER b
O
0
A
0
E
A
1
O
1
O
2
O
3
Pin Names
A
0
, A
1
Address Inputs
E
Enable Inputs
O
0
to
O
3
Outputs
HD74AC139/HD74ACT139
3
Logic Diagram
O
3b
O
2b
O
1b
O
0b
O
3a
O
2a
O
1a
O
0a
E
a
E
b
A
0a
A
1a
A
0b
A
1b
Please note that this diagram is provided only for the understanding of logic operations and should not be
used to estimate propagation delays.
Functional Description
The HD74AC139/HD74ACT139 is a high-speed dual 1-of-4 decoder/demultiplexer. The device has two
independent decoders, each of which accepts two binary weighted inputs (A
0
to A
1
) and provides four
mutually exclusive active-Low outputs (
O
0
to
O
3
). Each decoder has an active-Low enable (
E). When E is
High all outputs are forced High. The enable can be used as the data input for a 4-output demultiplexer
application. Each half of the HD74AC139/HD74ACT139 generates all four minterms of two variables.
These four minterms are useful in some applications, replacing multiple gate functions as shown in Figure
a, and thereby reducing the number of packages required in a logic network.
Truth Table
Inputs
Outputs
E
A
0
A
1
O
0
O
1
O
2
O
3
H
X
X
H
H
H
H
L
L
L
L
H
H
H
L
H
L
H
L
H
H
L
L
H
H
H
L
H
L
H
H
H
H
H
L
H :
High Voltage Level
L
:
Low Voltage Level
X :
Immaterial
HD74AC139/HD74ACT139
4
Figure a: Gate Functions (each half)
E
A
0
O
0
O
1
O
2
O
3
O
0
O
1
O
2
O
3
A
1
E
A
0
A
1
E
A
0
A
1
E
A
0
A
1
E
A
0
A
1
E
A
0
A
1
E
A
0
A
1
E
A
0
A
1
DC Characteristics (unless otherwise specified)
Item
Symbol
Max
Unit
Condition
Maximum quiescent supply current
I
CC
80
µ
A
V
IN
= V
CC
or ground, V
CC
= 5.5 V,
Ta = Worst case
Maximum quiescent supply current
I
CC
8.0
µ
A
V
IN
= V
CC
or ground, V
CC
= 5.5 V,
Ta = 25
°
C
Maximum I
CC
/input (HD74ACT139)
I
CCT
1.5
mA
V
IN
= V
CC
2.1 V, V
CC
= 5.5 V
Ta = Worst case
HD74AC139/HD74ACT139
5
AC Characteristics: HD74AC139
Ta = +25
°
C
C
L
= 50 pF
Ta = 40
°
C to +85
°
C
C
L
= 50 pF
Item
Symbol
V
CC
(V)*
1
Min
Typ
Max
Min
Max
Unit
Propagation delay
t
PLH
3.3
1.0
8.0
11.5
1.0
13.0
ns
A
n
to
O
n
5.0
1.0
6.5
8.5
1.0
9.5
Propagation delay
t
PHL
3.3
1.0
7.0
10.0
1.0
11.0
ns
A
n
to
O
n
5.0
1.0
5.5
7.5
1.0
8.5
Propagation delay
t
PLH
3.3
1.0
9.5
12.0
1.0
13.0
ns
E
n
to
O
n
5.0
1.0
7.0
8.5
1.0
10.0
Propagation delay
t
PHL
3.3
1.0
8.0
10.0
1.0
11.0
ns
E
n
to
O
n
5.0
1.0
6.0
7.5
1.0
8.5
Note:
1. Voltage Range 3.3 is 3.3 V
±
0.3 V
Voltage Range 5.0 is 5.0 V
±
0.5 V
AC Characteristics: HD74ACT139
Ta = +25
°
C
C
L
= 50 pF
Ta = 40
°
C to +85
°
C
C
L
= 50 pF
Item
Symbol
V
CC
(V)*
1
Min
Typ
Max
Min
Max
Unit
Propagation delay
A
n
to
O
n
t
PLH
5.0
1.0
6.0
8.5
1.0
9.5
ns
Propagation delay
A
n
to
O
n
t
PHL
5.0
1.0
6.0
9.5
1.0
10.5
ns
Propagation delay
E
n
to
O
n
t
PLH
5.0
1.0
7.0
10.0
1.0
11.0
ns
Propagation delay
E
n
to
O
n
t
PHL
5.0
1.0
7.0
9.5
1.0
10.5
ns
Note:
1. Voltage Range 5.0 is 5.0 V
±
0.5 V
Capacitance
Item
Symbol
Typ
Unit
Condition
Input capacitance
C
IN
4.5
pF
V
CC
= 5.5 V
Power dissipation capacitance
C
PD
40.0
pF
V
CC
= 5.0 V
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