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National Semiconductor Electronic Components Datasheet

DM54LS138 Datasheet

Decoders/Demultiplexers

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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 appli-
cations 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 intro-
duced by the decoder is negligible
The LS138 decodes one-of-eight lines based upon the con-
ditions 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 ex-
panding A 24-line decoder can be implemented with no ex-
ternal 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 de-
coders 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 in-
puts to simplify cascading and or data reception
Y LS139 contains two fully independent 2-to-4-line decod-
ers 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 Semicon-
ductor Sales Office Distributor for specifications
Connection Diagrams
Dual-in-Line Package
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
C1995 National Semiconductor Corporation TL F 6391
TL F 6391 – 2
Order Number 54LS139DMQB 54LS139FMQB
54LS139LMQB DM54LS139J DM54LS139W
DM74LS139M or DM74LS139N
See NS Package Number E20A J16A
M16A N16E or W16A
RRD-B30M105 Printed in U S A


National Semiconductor Electronic Components Datasheet

DM54LS138 Datasheet

Decoders/Demultiplexers

No Preview Available !

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
b55 C to a125 C
DM74LS
0 C to a70 C
Storage Temperature Range
b65 C to a150 C
Note The ‘‘Absolute Maximum Ratings’’ are those values
beyond which the safety of the device cannot be guaran-
teed 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
VCC
VIH
VIL
IOH
IOL
TA
Parameter
Supply Voltage
High Level Input Voltage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Free Air Operating Temperature
Min
45
2
b55
DM54LS138
Nom
Max
5 55
07
b0 4
4
125
Min
4 75
2
0
DM74LS138
Nom
Max
5 5 25
08
b0 4
8
70
Units
V
V
V
mA
mA
C
’LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
VI
VOH
Input Clamp Voltage
High Level Output
Voltage
VCC e Min II e b18 mA
VCC e Min IOH e Max
VIL e Max VIH e Min
DM54
DM74
25
27
VOL Low Level Output
Voltage
VCC e Min IOL e Max
VIL e Max VIH e Min
DM54
DM74
IOL e 4 mA VCC e Min
DM74
II
Input Current Max
VCC e Max VI e 7V
Input Voltage
IIH
High Level Input Current
VCC e Max VI e 2 7V
IIL
Low Level Input Current
VCC e Max VI e 0 4V
IOS Short Circuit
Output Current
VCC e Max
(Note 2)
DM54
DM74
b20
b20
ICC Supply Current
VCC e Max (Note 3)
Note 1 All typicals are at VCC e 5V TA 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 ICC is measured with all outputs enabled and open
Typ
(Note 1)
34
34
0 25
0 35
0 25
63
Max
b1 5
04
05
04
01
20
b0 36
b100
b100
10
Units
V
V
V
mA
mA
mA
mA
mA
2


Part Number DM54LS138
Description Decoders/Demultiplexers
Maker National Semiconductor
Total Page 8 Pages
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