Revised March 2000
DM74LS138 • DM74LS139
Decoder/Demultiplexer
General Description
Features
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.
■ Designed specifically for high speed:
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 inverters when expanding. A 24-line decoder can be implemented 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.
■ Typical propagation delay (3 levels of logic)
Memory decoders
Data transmission systems
■ DM74LS138 3-to-8-line decoders incorporates 3 enable
inputs to simplify cascading and/or data reception
■ DM74LS139 contains two fully independent 2-to-4-line
decoders/demultiplexers
■ Schottky clamped for high performance
DM74LS138
21 ns
DM74LS139
21 ns
■ Typical power dissipation
DM74LS138
32 mW
DM74LS139
34 mW
The DM74LS139 comprises two separate two-line-to-fourline decoders in a single package. The active-low enable
input can be used as a data line in demultiplexing applications.
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 system design.
Ordering Code:
Order Number
Package Number
Package Description
DM74LS138M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS138SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74LS138N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
DM74LS139M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS139SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74LS139N
N16E
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
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DM74LS138 • DM74LS139 Decoder/Demultiplexer
August 1986
DM74LS138 • DM74LS139
Connection Diagrams
DM74LS138
DM74LS139
Function Tables
DM74LS138
DM74LS139
Inputs
Enable
Inputs
Outputs
Select
Enable
G1 G2 (Note 1) C B A YO Y1 Y2 Y3 Y4 Y5 Y6 Y7
Outputs
Select
G
B
A
Y0
Y1
Y2
Y3
X
H
X X X
H
H
H
H
H
H
H
H
H
X
X
H
H
H
H
L
X
X X X
H
H
H
H
H
H
H
H
L
L
L
L
H
H
H
H
L
L L L
L
H
H
H
H
H
H
H
L
L
H
H
L
H
H
H
L
L L H
H
L
H
H
H
H
H
H
L
H
L
H
H
L
H
H
L
L H L
H
H
L
H
H
H
H
H
L
H
H
H
H
H
L
H
L
L H H
H
H
H
L
H
H
H
H
H
L
H L L
H
H
H
H
L
H
H
H
H
L
H L H
H
H
H
H
H
L
H
H
H
L
H H L
H
H
H
H
H
H
L
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
Logic Diagrams
DM74LS138
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DM74LS139
2
Supply Voltage
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.
7V
Input Voltage
7V
0°C to +70°C
Operating Free Air Temperature Range
−65°C to +150°C
Storage Temperature Range
DM74LS138 Recommended Operating Conditions
Symbol
Parameter
Min
Nom
Max
4.75
5
5.25
Units
VCC
Supply Voltage
VIH
HIGH Level Input Voltage
V
VIL
LOW Level Input Voltage
0.8
V
IOH
HIGH Level Output Current
−0.4
mA
IOL
LOW Level Output Current
8
mA
TA
Free Air Operating Temperature
70
°C
2
V
0
DM74LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
VI
Input Clamp Voltage
VCC = Min, II = −18 mA
VOH
HIGH Level Output Voltage
VCC = Min, IOH = Max, VIL = Max, VIH = Min
Typ
(Note 3)
Max
−1.5
2.7
3.4
Units
V
V
LOW Level
VCC = Min, IOL = Max, VIL = Max, VIH = Min
0.35
0.5
Output Voltage
IOL = 4 mA, VCC = Min
0.25
0.4
II
Input Current @ Max Input Voltage
VCC = Max, VI = 7V
0.1
IIH
HIGH Level Input Current
VCC = Max, VI = 2.7V
20
µA
IIL
LOW Level Input Current
VCC = Max, VI = 0.4V
−0.36
mA
IOS
Short Circuit Output Current
VCC = Max (Note 4)
ICC
Supply Current
VCC = Max (Note 5)
VOL
−20
V
mA
−100
mA
10
mA
6.3
Note 3: All typicals are at VCC = 5V, TA = 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: ICC is measured with all outputs enabled and OPEN.
DM74LS138 Switching Characteristics
at VCC = 5V and TA = 25°C
Symbol
Parameter
From (Input)
Levels
To (Output)
of Delay
RL = 2 kΩ
CL = 15 pF
Min
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
Max
CL = 50 pF
Min
Units
Max
Select to Output
2
18
27
ns
Select to Output
2
27
40
ns
Select to Output
3
18
27
ns
Select to Output
3
27
40
ns
Enable to Output
2
18
27
ns
Enable to Output
2
24
40
ns
Enable to Output
3
18
27
ns
Enable to Output
3
28
40
ns
3
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DM74LS138 • DM74LS139
Absolute Maximum Ratings(Note 2)
DM74LS138 • DM74LS139
DM74LS139 Recommended Operating Conditions
Symbol
Parameter
Min
Nom
Max
4.75
5
5.25
Units
VCC
Supply Voltage
VIH
HIGH Level Input Voltage
V
VIL
LOW Level Input Voltage
0.8
V
IOH
HIGH Level Output Current
−0.4
mA
IOL
LOW Level Output Current
8
mA
TA
Free Air Operating Temperature
70
°C
2
V
0
DM74LS139 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
VI
Input Clamp Voltage
VCC = Min, II = −18 mA
VOH
HIGH Level
VCC = Min, IOH = Max,
Output Voltage
VIL = Max, VIH = Min
VOL
LOW Level
VCC = Min, IOL = Max
Output Voltage
VIL = Max, VIH = Min
Min
2.7
IOL = 4 mA, VCC = Min
Typ
(Note 6)
Max
Units
−1.5
V
3.4
V
0.35
0.5
0.25
0.4
V
II
Input Current @ Max Input Voltage
VCC = Max, VI = 7V
0.1
IIH
HIGH Level Input Current
VCC = Max, VI = 2.7V
20
µA
IIL
LOW Level Input Current
VCC = Max, VI = 0.4V
−0.36
mA
IOS
Short Circuit Output Current
VCC = Max (Note 7)
ICC
Supply Current
VCC = Max (Note 8)
−20
6.8
mA
−100
mA
11
mA
Note 6: All typicals are at VCC = 5V, TA = 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: ICC is measured with all outputs enabled and OPEN.
DM74LS139 Switching Characteristics
at VCC = 5V and TA = 25°C
RL = 2 kΩ
From (Input)
Symbol
Parameter
CL = 15 pF
To (Output)
Min
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
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Max
CL = 50 pF
Min
Units
Max
Select to Output
18
27
ns
Select to Output
27
40
ns
Enable to Output
18
27
ns
Enable to Output
24
40
ns
4
DM74LS138 • DM74LS139
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
5
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DM74LS138 • DM74LS139
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
Package Number M16D
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6
DM74LS138 • DM74LS139 Decoder/Demultiplexer
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD
SEMICONDUCTOR CORPORATION. As used herein:
2. A critical component in any component of a life support
device or system whose failure to perform can be reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the
body, or (b) support or sustain life, and (c) whose failure
to perform when properly used in accordance with
instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the
user.
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