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DM74LS138 • DM74LS139
Decoder/Demultiplexer
DM74LS138 • DM74LS139 Decoder/Demultiplexer
August 1986
Revised March 2000
General Description
These Schottky-clamped circuits are designed to be used
in high-performance memory-decoding or data-routing
applications, requiring very short propagatio n delay times.
In high-performance memo ry systems these decoders can
be used to minimize the effects of system decoding. When
used with high-speed memories, the delay ti mes of these
decoders are usually less th an 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 fo r external gate s or inverters when expanding. A 24-line decoder can be implemented with no exte rnal inverters, and a 32-line de coder
requires only one inverter. An enable input can be used as
a data input for demultiplexing applications.
The DM74LS139 comprises tw o separate two-line-to- fourline decoders in a single package. The active-low enable
input can be used as a d ata lin e i n dem ultipl exing a pplic ations.
All of these decoders/d emultiplexers feature fu lly buffered
inputs, presenting on ly one normalized load to its driving
circuit. All inputs are clamped with high-performance
Schottky diodes to suppress lin e-ringing and simplify system design.
Features
■ Designed specifically for high speed:
Memory decoders
Data transmission systems
■ DM74LS138 3-to-8-li ne deco ders incorp orates 3 enable
inputs to simplify cascading and/or data reception
■ DM74LS139 contains tw o fully independent 2-t o-4-line
decoders/demultiple xers
■ Schottky clamped for high performance
■ Typical propagation delay (3 levels of logic)
DM74LS138 21 ns
DM74LS139 21 ns
■ Typical power dissipation
DM74LS138 32 mW
DM74LS139 34 mW
Ordering Code:
Order Number Package Number Package Description
DM74LS138M M16A 16-Lead Small Outlin e Integrated Circuit (SO IC), JEDEC MS-012, 0.150 Narrow
DM74LS138SJ M16D 16-Lead Small Out line 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 Outlin e Integrated Circuit (SO IC), JEDEC MS-012, 0.150 Narrow
DM74LS139SJ M16D 16-Lead Small Out line 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 availab le in Tape and Reel. Specify by appending th e s uffix let t er “X” to the ordering cod e.
© 2000 Fairchild Semiconductor Corporation DS006391 www.fairchildsemi.com
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Connection Diagrams
DM74LS138 DM74LS139
DM74LS138 • DM74LS139
Function Tables
DM74LS138 DM74LS139
Inputs
Enable Select
G1G2 (Note 1)CBAYOY1Y2Y3Y4Y5Y6Y7
X H XXXHHHHHHHH
L X XXXHHHHHHHH
H L LLLL HHHHHHH
H L LLHHLHHHHHH
H L LHLHHLHHHHH
H L LHHHHHLHHHH
H L HLLHHHHLHHH
H L HLHHHHHHLHH
H L HHLH HHHHHLH
H L HHHHHHHHHHL
Outputs
Inputs
Enable Select
G BAY0Y1Y2Y3
HXXHHHH
LLLLHHH
LLHHLHH
LHLHHLH
LHHHHHL
H = HIGH Level
L = LOW Level
X = Don’t Care
Note 1: G2 = G2A + G2B
Outputs
Logic Diagrams
DM74LS138 DM74LS139
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Absolute Maximum Ratings(Note 2)
Supply Voltage 7V
Input Voltage 7V
Operating Free Air Temperature Range 0°C to +70°C
Storage Temperature Range −65°C to +150°C
Note 2: The “Absolute Maximum Ratings ” are those val ues beyond w hich
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 “Recommend ed O peratin g Cond itions” t able w ill defin e the condit ions
for actual device operation.
DM74LS138 Recommended Operating Conditions
Symbol Parameter Min Nom Max Units
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage 4.75 5 5.25 V
HIGH Level Input Voltage 2 V
LOW Level In put Voltage 0.8 V
HIGH Level Output Current −0.4 mA
LOW Level Output Current 8 mA
Free Air Oper ating Temperature 0 70 °C
DM74LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min
V
I
V
OH
V
OL
I
I
I
IH
I
IL
I
OS
I
CC
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 exc eed one second.
Note 5: I
Input Clamp Voltage VCC = Min, II = −18 mA −1.5 V
HIGH Level Output Voltage VCC = Min, IOH = Max, VIL = Max, VIH = Min 2.7 3.4 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
Input Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 mA
HIGH Level Input Current VCC = Max, VI = 2.7V 20 µA
LOW Level Input Current VCC = Max, VI = 0.4V −0.36 mA
Short Circuit Output Current VCC = Max (Note 4) −20 −100 mA
Supply Current VCC = Max (Note 5) 6.3 10 mA
is measured with all out puts enabled and OPEN.
CC
Typ
(Note 3)
Max Units
DM74LS138 • DM74LS139
V
DM74LS138 Switching Characteristics
at VCC = 5V and TA = 25°C
Symbol Parameter
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
From (Input) Levels
To (Output) of Delay
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
RL = 2 kΩ
CL = 15 pF CL = 50 pF Units
Min Max Min Max
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DM74LS139 Recommended Operating Conditions
Symbol Parameter Min Nom Max Units
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage 4.75 5 5.25 V
HIGH Level Input Voltage 2 V
LOW Level In put Voltage 0.8 V
HIGH Level Output Current −0.4 mA
LOW Level Ou tput Current 8 mA
Free Air Operating Temperature 0 70 °C
DM74LS139 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
DM74LS138 • DM74LS139
Symbol Parameter Conditions Min
V
I
V
OH
V
OL
I
I
I
IH
I
IL
I
OS
I
CC
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: I
Input Clamp Voltage VCC = Min, II = −18 mA −1.5 V
HIGH Level VCC = Min, IOH = Max,
Output Voltage VIL = Max, VIH = Min
LOW Level VCC = Min, IOL = Max
Output Voltage VIL = Max, VIH = Min V
Input Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 mA
HIGH Level Input Current VCC = Max, VI = 2.7V 20 µA
LOW Level Input Current VCC = Max, VI = 0.4V −0.36 mA
Short Circuit Output Current VCC = Max (Note 7) −20 −100 mA
Supply Current VCC = Max (Note 8) 6.8 11 mA
is measured with all out puts enabled and OPEN.
CC
IOL = 4 mA, VCC = Min 0.25 0.4
2.7 3.4 V
Typ
(Note 6)
0.35 0.5
DM74LS139 Switching Characteristics
at VCC = 5V and TA = 25°C
Symbol Parameter
t
t
t
t
PLH
PHL
PLH
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
From (Input)
To (Outpu t)
Select to Output 18 27 ns
Select to Output 27 40 ns
Enable to Output 18 27 ns
Enable to Output 24 40 ns
CL = 15 pF CL = 50 pF Units
MinMaxMinMax
RL = 2 kΩ
Max Units
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Physical Dimensions inches (millimeters) unless otherwise noted
DM74LS138 • DM74LS139
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
DM74LS138 • DM74LS139
16-Lead Small Outline Package ( SOP), EIAJ TYPE II, 5.3mm Wide
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Package Number M16D
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
DM74LS138 • DM74LS139 Decoder/Demultiplexer
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent license s are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
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:
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 provide d in the labe l ing, can be re asonably expected to result in a significant injury to the
user.
Package Number N16E
2. A critical componen t in any com ponen t of a life s upport
device or system whose failu re to perform can b e reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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