74LS138

74LS138
DM74LS138, DM74LS139
Decoders/Demultiplexers
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 LS138 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.
The LS139 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 applications.
cuit. All inputs are clamped with high-performance Schottky
diodes to suppress line-ringing and simplify system design.
Features
n Designed specifically for high speed:
Memory decoders
Data transmission systems
n LS138 3-to-8-line decoders incorporates 3 enable inputs
to simplify cascading and/or data reception
n LS139 contains two fully independent 2-to-4-line
decoders/demultiplexers
n Schottky clamped for high performance
n Typical propagation delay (3 levels of logic)
LS138 21 ns
LS139 21 ns
n Typical power dissipation
LS138 32 mW
LS139 34 mW
n Alternate Military/Aerospace devices (54LS138,
54LS139) are available. Contact a Fairchild
Semiconductor Sales Office/Distributor for specifications.
All of these decoders/demultiplexers feature fully buffered inputs, presenting only one normalized load to its driving cir-
Connection Diagrams
Dual-In-Line Package
Dual-In-Line Package
DS006391-1
Order Number 54LS138DMQB, 54LS138FMQB,
54LS138LMQB, DM54LS138J, DM54LS138W,
DM74LS138M or DM74LS138N
See Package Number E20A, J16A,
M16A, N16E or W16A
Dual-in-Line Package
© 1998 Fairchild Semiconductor Corporation
DS006391
DS006391-2
Order Number 54LS139DMQB, 54LS139FMQB,
54LS139LMQB, DM54LS139J, DM54LS139W,
DM74LS139M or DM74LS139N
See Package Number E20A, J16A,
M16A, N16E or W16A
www.fairchildsemi.com
DM74LS138, DM74LS139 Decoders/Demultiplexers
March 1998
Absolute Maximum Ratings (Note 1)
Supply Voltage
Input Voltage
Operating Free Air Temperature Range
DM54LS and 54LS
DM74LS
Storage Temperature Range
7V
7V
−55˚C to +125˚C
0˚C to +70˚C
−65˚C to +150˚C
Recommended Operating Conditions
Symbol
Parameter
DM54LS138
DM74LS138
Units
Min
Nom
Max
Min
Nom
Max
4.5
5
5.5
4.75
5
5.25
VCC
Supply Voltage
VIH
High Level Input Voltage
VIL
Low Level Input Voltage
0.7
0.8
V
IOH
High Level Output Current
−0.4
−0.4
mA
IOL
Low Level Output Current
8
mA
TA
Free Air Operating Temperature
70
˚C
2
2
V
4
−55
125
V
0
Note 1: 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” table are not guaranteed at the absolute maximum ratings. The “Recommended Operating
Conditions” table will define the conditions for actual device operation.
’LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
−1.5
V
(Note 2)
VI
Input Clamp Voltage
VOH
High Level Output
Voltage
VOL
Low Level Output
Voltage
Input Current @ Max
II
VCC = Min, II = −18 mA
VCC = Min, IOH = Max,
VIL = Max, VIH = Min
VCC = Min, IOL = Max,
VIL = Max, VIH = Min
IOL = 4 mA, VCC = Min
DM54
2.5
3.4
DM74
2.7
3.4
V
DM54
0.25
DM74
0.35
0.5
DM74
0.25
0.4
VCC = Max, VI = 7V
0.4
0.1
V
mA
Input Voltage
IIH
High Level Input Current
IIL
Low Level Input Current
IOS
Short Circuit
Output Current
ICC
Supply Current
VCC = Max, VI = 2.7V
VCC = Max, VI = 0.4V
VCC = Max
(Note 3)
VCC = Max (Note 4)
20
µA
−0.36
mA
mA
DM54
−20
−100
DM74
−20
−100
6.3
10
mA
Note 2: All typicals are at VCC = 5V, TA = 25˚C.
Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 4: ICC is measured with all outputs enabled and open.
’LS138 Switching Characteristics
at VCC = 5V and TA = 25˚C
Symbol
Parameter
From (Input)
Levels
To (Output)
of Delay
RL = 2 kΩ
CL = 50 pF
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
www.fairchildsemi.com
Select to
Max
Min
Units
Max
2
18
27
ns
2
27
40
ns
3
18
27
ns
Output
Select to
Output
Select to
Output
2
’LS138 Switching Characteristics
(Continued)
at VCC = 5V and TA = 25˚C
Symbol
Parameter
From (Input)
Levels
To (Output)
of Delay
RL = 2 kΩ
CL = 50 pF
CL = 15 pF
Min
tPHL
Propagation Delay Time
Select to
High to Low Level Output
tPLH
Propagation Delay Time
Enable to
Propagation Delay Time
Enable to
3
27
40
ns
2
18
27
ns
2
24
40
ns
3
18
27
ns
3
28
40
ns
Output
Propagation Delay Time
Enable to
Low to High Level Output
tPHL
Units
Max
Output
High to Low Level Output
tPLH
Min
Output
Low to High Level Output
tPHL
Max
Output
Propagation Delay Time
Enable to
High to Low Level Output
Output
Recommended Operating Conditions
Symbol
Parameter
DM54LS139
DM74LS139
Units
Min
Nom
Max
Min
Nom
Max
4.5
5
5.5
4.75
5
5.25
VCC
Supply Voltage
VIH
High Level Input Voltage
VIL
Low Level Input Voltage
0.7
0.8
V
IOH
High Level Output Current
−0.4
−0.4
mA
IOL
Low Level Output Current
8
mA
TA
Free Air Operating Temperature
70
˚C
2
2
V
4
−55
125
V
0
’LS139 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
−1.5
V
(Note 5)
VI
Input Clamp Voltage
VOH
High Level Output
Voltage
VOL
Low Level Output
Voltage
Input Current @ Max
II
VCC = Min, II = −18 mA
VCC = Min, IOH = Max,
VIL = Max, VIH = Min
VCC = Min, IOL = Max
VIL = Max, VIH = Min
IOL = 4 mA, VCC = Min
DM54
2.5
3.4
DM74
2.7
3.4
V
DM54
0.25
DM74
0.35
0.5
DM74
0.25
0.4
VCC = Max, VI = 7V
0.4
0.1
V
mA
Input Voltage
IIH
High Level Input Current
IIL
Low Level Input Current
IOS
Short Circuit
Output Current
ICC
Supply Current
VCC = Max, VI = 2.7V
VCC = Max, VI = 0.4V
VCC = Max
(Note 6)
VCC = Max (Note 7)
20
µA
−0.36
mA
mA
DM54
−20
−100
DM74
−20
−100
6.8
11
mA
Note 5: All typicals are at VCC = 5V, TA = 25˚C.
Note 6: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 7: ICC is measured with all outputs enabled and open.
3
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’LS139 Switching Characteristics
at VCC = 5V and TA = 25˚C
RL = 2 kΩ
From (Input)
Symbol
Parameter
CL = 15 pF
To (Output)
Min
Propagation Delay Time
tPLH
Select to
Low to High Level Output
tPHL
Select to
High to Low Level Output
Enable to
Low to High Level Output
Enable to
High to Low Level Output
Output
Function Tables
LS138
Inputs
G1
Outputs
Select
G2 (Note 8) C B A YO Y1 Y2 Y3 Y4 Y5 Y6 Y7
X
H
X X X
H
H
H
H
H
H
H
H
L
X
X X X
H
H
H
H
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L H
H
L
H
H
H
H
H
H
H
L
L H
H
H
L
H
H
H
H
H
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
L
H = High Level, L = Low Level, X = Don’t Care
Note 8: G2 = G2A + G2B
LS139
Inputs
Enable
Outputs
Select
G
B
A
Y0
Y1
Y2
Y3
H
X
X
H
H
H
H
L
L
L
L
H
H
H
L
L
H
H
L
H
H
L
H
L
H
H
L
H
L
H
H
H
H
H
L
H = High Level, L = Low Level, X = Don’t Care
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18
27
ns
27
40
ns
18
27
ns
24
40
ns
Output
Propagation Delay Time
Enable
Units
Max
Output
Propagation Delay Time
tPHL
CL = 50 pF
Min
Output
Propagation Delay Time
tPLH
Max
4
Logic Diagrams
LS138
DS006391-3
LS139
DS006391-4
5
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Physical Dimensions
inches (millimeters) unless otherwise noted
Ceramic Leadless Chip Carrier Package (E)
Order Number 54LS138LMQB or 54LS139LMQB
Package Number E20A
16-Lead Ceramic Dual-In-Line Package (J)
Order Number 54LS138DMQB, 54LS139DMQB, DM54LS138J or DM54LS139J
Package Number J16A
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6
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
16-Lead Small Outline Molded Package (M)
Order Number DM74LS138M or DM74LS139M
Package Number M16A
16-Lead Molded Dual-In-Line Package (N)
Order Number DM74LS138N or DM74LS139N
Package Number N16E
7
www.fairchildsemi.com
DM74LS138, DM74LS139 Decoders/Demultiplexers
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
16-Lead Ceramic Flat Package (W)
Order Number 54LS138FMQB, 54LS139FMQB, DM54LS138W or DM54LS139W
Package Number W16A
LIFE SUPPORT POLICY
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
1. Life support devices or systems are devices or sysdevice or system whose failure to perform can be reatems which, (a) are intended for surgical implant into
sonably expected to cause the failure of the life support
the body, or (b) support or sustain life, and (c) whose
device or system, or to affect its safety or effectiveness.
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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Tel: 1-888-522-5372
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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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