NSC DM54LS138W-883, DM54LS138J-883, DM54LS138E-883 Datasheet
TL/F/6391
54LS138/DM54LS138/DM74LS138,
54LS139/DM54LS139/DM74LS139 Decoders/Demultiplexers
June 1989
54LS138/DM54LS138/DM74LS138,
54LS139/DM54LS139/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.
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.
Features
Y
Designed specifically for high speed:
Memory decoders
Data transmission systems
Y
LS138 3-to-8-line decoders incorporates 3 enable inputs to simplify cascading and/or data reception
Y
LS139 contains two fully independent 2-to-4-line decoders/demultiplexers
Y
Schottky clamped for high performance
Y
Typical propagation delay (3 levels of logic)
LS138 21 ns
LS139 21 ns
Y
Typical power dissipation
LS138 32 mW
LS139 34 mW
Y
Alternate Military/Aerospace devices (54LS138,
54LS139) are available. Contact a National Semiconductor Sales Office/Distributor for specifications.
Connection Diagrams
Dual-in-Line Package
TL/F/6391– 1
Order Number 54LS138DMQB, 54LS138FMQB,
54LS138LMQB, DM54LS138J, DM54LS138W,
DM74LS138M or DM74LS138N
See NS Package Number E20A, J16A,
M16A, N16E or W16A
Dual-in-Line Package
TL/F/6391– 2
Order Number 54LS139DMQB, 54LS139FMQB,
54LS139LMQB, DM54LS139J, DM54LS139W,
DM74LS139M or DM74LS139N
See NS Package Number E20A, J16A,
M16A, N16E or W16A
C
1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.
Absolute Maximum Ratings (Note)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage 7V
Input Voltage 7V
Operating Free Air Temperature Range
DM54LS and 54LS
b
55§Ctoa125§C
DM74LS 0
§
Ctoa70§C
Storage Temperature Range
b
65§Ctoa150§C
Note:
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.
Recommended Operating Conditions
Symbol Parameter
DM54LS138 DM74LS138
Units
Min Nom Max Min Nom Max
V
CC
Supply Voltage 4.5 5 5.5 4.75 5 5.25 V
V
IH
High Level Input Voltage 2 2 V
V
IL
Low Level Input Voltage 0.7 0.8 V
I
OH
High Level Output Current
b
0.4
b
0.4 mA
I
OL
Low Level Output Current 4 8 mA
T
A
Free Air Operating Temperature
b
55 125 0 70
§
C
’LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min
Typ
Max Units
(Note 1)
V
I
Input Clamp Voltage V
CC
e
Min, I
I
eb
18 mA
b
1.5 V
V
OH
High Level Output V
CC
e
Min, I
OH
e
Max, DM54 2.5 3.4
V
Voltage V
IL
e
Max, V
IH
e
Min
DM74 2.7 3.4
V
OL
Low Level Output V
CC
e
Min, I
OL
e
Max, DM54 0.25 0.4
Voltage V
IL
e
Max, V
IH
e
Min
DM74 0.35 0.5 V
I
OL
e
4 mA, V
CC
e
Min DM74 0.25 0.4
I
I
Input Current@Max V
CC
e
Max, V
I
e
7V
0.1 mA
Input Voltage
I
IH
High Level Input Current V
CC
e
Max, V
I
e
2.7V 20 mA
I
IL
Low Level Input Current V
CC
e
Max, V
I
e
0.4V
b
0.36 mA
I
OS
Short Circuit V
CC
e
Max DM54
b
20
b
100
mA
Output Current (Note 2)
DM74
b
20
b
100
I
CC
Supply Current V
CC
e
Max (Note 3) 6.3 10 mA
Note 1: All typicals are at V
CC
e
5V, T
A
e
25§C.
Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 3: I
CC
is measured with all outputs enabled and open.
2
’LS138 Switching Characteristics
at V
CC
e
5V and T
A
e
25§C (See Section 1 for Test Waveforms and Output Load)
From (Input) Levels
R
L
e
2kX
Symbol Parameter
To (Output) of Delay
C
L
e
15 pF C
L
e
50 pF Units
Min Max Min Max
t
PLH
Propagation Delay Time Select to
21827ns
Low to High Level Output Output
t
PHL
Propagation Delay Time Select to
22740ns
High to Low Level Output Output
t
PLH
Propagation Delay Time Select to
31827ns
Low to High Level Output Output
t
PHL
Propagation Delay Time Select to
32740ns
High to Low Level Output Output
t
PLH
Propagation Delay Time Enable to
21827ns
Low to High Level Output Output
t
PHL
Propagation Delay Time Enable to
22440ns
High to Low Level Output Output
t
PLH
Propagation Delay Time Enable to
31827ns
Low to High Level Output Output
t
PHL
Propagation Delay Time Enable to
32840ns
High to Low Level Output Output
Recommended Operating Conditions
Symbol Parameter
DM54LS139 DM74LS139
Units
Min Nom Max Min Nom Max
V
CC
Supply Voltage 4.5 5 5.5 4.75 5 5.25 V
V
IH
High Level Input Voltage 2 2 V
V
IL
Low Level Input Voltage 0.7 0.8 V
I
OH
High Level Output Current
b
0.4
b
0.4 mA
I
OL
Low Level Output Current 4 8 mA
T
A
Free Air Operating Temperature
b
55 125 0 70
§
C
3
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