DM74LS138 * DM74LS139 Decoder/Demultiplexer 74138 139

User Manual: 74138-139

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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

www.fairchildsemi.com

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

www.fairchildsemi.com

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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Title                           : DM74LS138 * DM74LS139 Decoder/Demultiplexer

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