DM74LS138 * DM74LS139 Decoder/Demultiplexer 74138 139
User Manual: 74138-139
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© 2000 Fairchild Semiconductor Corporation DS006391 www.fairchildsemi.com
August 1986
Revised March 2000
DM74LS138 • DM74LS139 Decoder/Demultiplexer
DM74LS138 • DM74LS139
Decoder/Demultiplexer
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 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 invert-
ers when expanding. A 24-line decoder can be imple-
mented 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 DM74LS139 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 applica-
tions.
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 sys-
tem design.
Features
■Designed specifically for high speed:
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
■Typical propagation delay (3 levels of logic)
DM74LS138 21 ns
DM74LS139 21 ns
■Typical power dissipation
DM74LS138 32 mW
DM74LS139 34 mW
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the 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
www.fairchildsemi.com 2
DM74LS138 • DM74LS139
Connection Diagrams
DM74LS138 DM74LS139
Function Tables
DM74LS138 DM74LS139
H = HIGH Level
L = LOW Level
X = Don’t Care
Note 1: G2 = G2A + G2B
Logic Diagrams
DM74LS138 DM74LS139
Inputs Outputs
Enable Select
G1G2 (Note 1)CBAYOY1Y2Y3Y4Y5Y6Y7
X H XXXH HHHHHHH
L X XXXH HHHHHHH
H L LLLL HHHHHHH
H L LLHH LHHHHHH
H L LHLH HLHHHHH
H L LHHH HHL HHHH
H L HLLH HHHLHHH
H L HLHH HHHHLHH
H L HHLH HHHHH LH
H L HHHH HHHHHHL
Inputs Outputs
Enable Select
G BAY0Y1Y2Y3
HXXHHHH
LLLLHHH
LLHHLHH
LHLHHLH
LHHHHHL
3 www.fairchildsemi.com
DM74LS138 • DM74LS139
Absolute Maximum Ratings(Note 2)
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.
DM74LS138 Recommended Operating Conditions
DM74LS138 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
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
Supply Voltage 7V
Input Voltage 7V
Operating Free Air Temperature Range 0°C to +70°C
Storage Temperature Range −65°C to +150°C
Symbol Parameter Min Nom Max Units
VCC Supply Voltage 4.75 5 5.25 V
VIH HIGH Level Input Voltage 2 V
VIL LOW Level Input Voltage 0.8 V
IOH HIGH Level Output Current −0.4 mA
IOL LOW Level Output Current 8 mA
TAFree Air Operating Temperature 0 70 °C
Symbol Parameter Conditions Min Typ Max Units
(Note 3)
VIInput Clamp Voltage VCC = Min, II = −18 mA −1.5 V
VOH HIGH Level Output Voltage VCC = Min, IOH = Max, VIL = Max, VIH = Min 2.7 3.4 V
VOL LOW Level VCC = Min, IOL = Max, VIL = Max, VIH = Min 0.35 0.5 V
Output Voltage IOL = 4 mA, VCC = Min 0.25 0.4
IIInput Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 mA
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) −20 −100 mA
ICC Supply Current VCC = Max (Note 5) 6.3 10 mA
From (Input) Levels RL = 2 kΩ
Symbol Parameter To (Output) of Delay CL = 15 pF CL = 50 pF Units
Min Max Min Max
tPLH Propagation Delay Time Select to Output 2 18 27 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time Select to Output 2 27 40 ns
HIGH-to-LOW Level Output
tPLH Propagation Delay Time Select to Output 3 18 27 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time Select to Output 3 27 40 ns
HIGH-to-LOW Level Output
tPLH Propagation Delay Time Enable to Output 2 18 27 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time Enable to Output 2 24 40 ns
HIGH-to-LOW Level Output
tPLH Propagation Delay Time Enable to Output 3 18 27 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time Enable to Output 3 28 40 ns
HIGH-to-LOW Level Output
www.fairchildsemi.com 4
DM74LS138 • DM74LS139
DM74LS139 Recommended Operating Conditions
DM74LS139 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
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
Symbol Parameter Min Nom Max Units
VCC Supply Voltage 4.75 5 5.25 V
VIH HIGH Level Input Voltage 2 V
VIL LOW Level Input Voltage 0.8 V
IOH HIGH Level Output Current −0.4 mA
IOL LOW Level Output Current 8 mA
TAFree Air Operating Temperature 0 70 °C
Symbol Parameter Conditions Min Typ Max Units
(Note 6)
VIInput Clamp Voltage VCC = Min, II = −18 mA −1.5 V
VOH HIGH Level VCC = Min, IOH = Max, 2.7 3.4 V
Output Voltage VIL = Max, VIH = Min
VOL LOW Level VCC = Min, IOL = Max 0.35 0.5
Output Voltage VIL = Max, VIH = Min V
IOL = 4 mA, VCC = Min 0.25 0.4
IIInput Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 mA
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) −20 −100 mA
ICC Supply Current VCC = Max (Note 8) 6.8 11 mA
From (Input) RL = 2 kΩ
Symbol Parameter To (Output) CL = 15 pF CL = 50 pF Units
MinMaxMinMax
tPLH Propagation Delay Time Select to Output 18 27 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time Select to Output 27 40 ns
HIGH-to-LOW Level Output
tPLH Propagation Delay Time Enable to Output 18 27 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time Enable to Output 24 40 ns
HIGH-to-LOW Level Output
5 www.fairchildsemi.com
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
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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
7 www.fairchildsemi.com
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:
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 rea-
sonably expected to result in a significant injury to the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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