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DM74LS138 • DM74LS139 Decoder/Demultiplexer
August 1986
Revised March 2000
DM74LS138 • DM74LS139
Decoder/Demultiplexer
General Description
These Schottky-clamped circuits are designed to be used
in high-performance memory-decoding or data-routing
applications, requiring very short propagation delay times.
In high-performance memory systems these decoders can
be used to minimize the effects of system decoding. When
used with high-speed memories, the delay times of these
decoders are usually less than the typical access time of
the memory. This means that the effective system delay
introduced by the decoder is negligible.
The DM74LS138 decodes one-of-eight lines, based upon
the conditions at the three binary select inputs and the
three enable inputs. Two active-low and one active-high
enable inputs reduce the need for external gates or invert-
ers when expanding. A 24-line decoder can be imple-
mented with no external inverters, and a 32-line decoder
requires only one inverter. An enable input can be used as
a data input for demultiplexing applications.
The DM74LS139 comprises two separate two-line-to-four-
line decoders in a single package. The active-low enable
input can be used as a data line in demultiplexing applica-
tions.
All of these decoders/demultiplexers feature fully buffered
inputs, presenting only one normalized load to its driving
circuit. All inputs are clamped with high-performance
Schottky diodes to suppress line-ringing and simplify sys-
tem design.
Features
s
Designed specifically for high speed:
Memory decoders
Data transmission systems
s
DM74LS138 3-to-8-line decoders incorporates 3 enable
inputs to simplify cascading and/or data reception
s
DM74LS139 contains two fully independent 2-to-4-line
decoders/demultiplexers
s
Schottky clamped for high performance
s
Typical propagation delay (3 levels of logic)
DM74LS138
DM74LS139
DM74LS138
DM74LS139
21 ns
21 ns
32 mW
34 mW
s
Typical power dissipation
Ordering Code:
Order Number
DM74LS138M
DM74LS138SJ
DM74LS138N
DM74LS139M
DM74LS139SJ
DM74LS139N
Package Number
M16A
M16D
N16E
M16A
M16D
N16E
Package Description
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
© 2000 Fairchild Semiconductor Corporation
DS006391
www.fairchildsemi.com
DM74LS138 • DM74LS139
Connection Diagrams
DM74LS138
DM74LS139
Function Tables
DM74LS138
Inputs
Enable
X
L
H
H
H
H
H
H
H
H
H
X
L
L
L
L
L
L
L
L
Select
X X X
X X X
L L L
L L H
L H L
L H H
H L L
H L H
H H L
H H H
H
H
L
H
H
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
L
H
H
H
H
H
Outputs
Inputs
Enable
G
H
L
L
L
L
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
L
H
=
HIGH Level
L
=
LOW Level
X
=
Don’t Care
Note 1:
G2
=
G2A
+
G2B
DM74LS139
Outputs
Y0
H
L
H
H
H
Y1
H
H
L
H
H
Y2
H
H
H
L
H
Y3
H
H
H
H
L
Select
B
X
L
L
H
H
A
X
L
H
L
H
G1 G2 (Note 1) C B A YO Y1 Y2 Y3 Y4 Y5 Y6 Y7
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
L
H
H
H
Logic Diagrams
DM74LS138
DM74LS139
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2
DM74LS138 • DM74LS139
Absolute Maximum Ratings
(Note 2)
Supply Voltage
Input Voltage
Operating Free Air Temperature Range
Storage Temperature Range
7V
7V
0°C to
+70°C
−65°C
to
+150°C
Note 2:
The “Absolute Maximum Ratings” are those values beyond which
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the Electrical
Characteristics tables are not guaranteed at the absolute maximum ratings.
The “Recommended Operating Conditions” table will define the conditions
for actual device operation.
DM74LS138 Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
0
Parameter
Min
4.75
2
0.8
−0.4
8
70
Nom
5
Max
5.25
Units
V
V
V
mA
mA
°C
DM74LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
V
OH
V
OL
I
I
I
IH
I
IL
I
OS
I
CC
Parameter
Input Clamp Voltage
HIGH Level Output Voltage
LOW Level
Output Voltage
Input Current @ Max Input Voltage
HIGH Level Input Current
LOW Level Input Current
Short Circuit Output Current
Supply Current
Conditions
V
CC
=
Min, I
I
= −18
mA
V
CC
=
Min, I
OH
=
Max, V
IL
=
Max, V
IH
=
Min
V
CC
=
Min, I
OL
=
Max, V
IL
=
Max, V
IH
=
Min
I
OL
=
4 mA, V
CC
=
Min
V
CC
=
Max, V
I
=
7V
V
CC
=
Max, V
I
=
2.7V
V
CC
=
Max, V
I
=
0.4V
V
CC
=
Max (Note 4)
V
CC
=
Max (Note 5)
−20
6.3
2.7
3.4
0.35
0.25
0.5
0.4
0.1
20
−0.36
−100
10
Min
Typ
(Note 3)
Max
−1.5
Units
V
V
V
mA
µA
mA
mA
mA
Note 3:
All typicals are at V
CC
=
5V, T
A
=
25°C.
Note 4:
Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 5:
I
CC
is measured with all outputs enabled and OPEN.
DM74LS138 Switching Characteristics
at V
CC
=
5V and T
A
=
25°C
From (Input)
Symbol
Parameter
To (Output)
Levels
of Delay
C
L
=
15 pF
Min
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Select to Output
Select to Output
Select to Output
Select to Output
Enable to Output
Enable to Output
Enable to Output
Enable to Output
2
2
3
3
2
2
3
3
Max
18
27
18
27
18
24
18
28
R
L
=
2 kΩ
C
L
=
50 pF
Min
Max
27
40
27
40
27
40
27
40
ns
ns
ns
ns
ns
ns
ns
ns
Units
3
www.fairchildsemi.com
DM74LS138 • DM74LS139
DM74LS139 Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
0
Parameter
Min
4.75
2
0.8
−0.4
8
70
Nom
5
Max
5.25
Units
V
V
V
mA
mA
°C
DM74LS139 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
V
OH
V
OL
Parameter
Input Clamp Voltage
HIGH Level
Output Voltage
LOW Level
Output Voltage
I
I
I
IH
I
IL
I
OS
I
CC
Input Current @ Max Input Voltage
HIGH Level Input Current
LOW Level Input Current
Short Circuit Output Current
Supply Current
Conditions
V
CC
=
Min, I
I
= −18
mA
V
CC
=
Min, I
OH
=
Max,
V
IL
=
Max, V
IH
=
Min
V
CC
=
Min, I
OL
=
Max
V
IL
=
Max, V
IH
=
Min
I
OL
=
4 mA, V
CC
=
Min
V
CC
=
Max, V
I
=
7V
V
CC
=
Max, V
I
=
2.7V
V
CC
=
Max, V
I
=
0.4V
V
CC
=
Max (Note 7)
V
CC
=
Max (Note 8)
−20
6.8
2.7
3.4
0.35
0.25
0.5
0.4
0.1
20
−0.36
−100
11
mA
µA
mA
mA
mA
Min
Typ
(Note 6)
Max
−1.5
Units
V
V
V
Note 6:
All typicals are at V
CC
=
5V, T
A
=
25°C.
Note 7:
Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 8:
I
CC
is measured with all outputs enabled and OPEN.
DM74LS139 Switching Characteristics
at V
CC
=
5V and T
A
=
25°C
From (Input)
Symbol
Parameter
To (Output)
C
L
=
15 pF
Min
t
PLH
t
PHL
t
PLH
t
PHL
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Select to Output
Select to Output
Enable to Output
Enable to Output
Max
18
27
18
24
R
L
=
2 kΩ
C
L
=
50 pF
Min
Max
27
40
27
40
ns
ns
ns
ns
Units
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