© 2000 Fairchild Semiconductor Corporation
DS006395
www.fairchildsemi.com
August 1986
Revised April 2000
DM74LS155
·
D
M
74LS15
6 Dual
2-
Li
ne t
o
4-
Li
ne Decod
ers/
Dem
u
l
t
i
p
l
exers
DM74LS155 · DM74LS156
Dual 2-Line to 4-Line Decoders/Demultiplexers
General Description
These TTL circuits feature dual 1-line-to-4-line demultiplex-
ers with individual strobes and common binary-address
inputs in a single 16-pin package. When both sections are
enabled by the strobes, the common address inputs
sequentially select and route associated input data to the
appropriate output of each section. The individual strobes
permit activating or inhibiting each of the 4-bit sections as
desired. Data applied to input C1 is inverted at its outputs
and data applied at C2 is true through its outputs. The
inverter following the C1 data input permits use as a 3-to-8-
line decoder, or 1-to-8-line demultiplexer, without external
gating. Input clamping diodes are provided on these cir-
cuits to minimize transmission-line effects and simplify sys-
tem design.
Features
s
Applications:
Dual 2-to-4-line decoder
Dual 1-to-4-line demultiplexer
3-to-8-line decoder
1-to-8-line demultiplexer
s
Individual strobes simplify cascading for decoding or
demultiplexing larger words
s
Input clamping diodes simplify system design
s
Choice of outputs:
Totem-pole (DM74LS155)
Open-collector (DM74LS156)
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Connection Diagram
Order Number
Package Number
Package Description
DM74LS155M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS155N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
DM74LS156M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS156N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
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2
DM74LS155
· DM74LS156
Function Tables
3-Line-to-8-Line Decoder or 1-Line-to-8-Line Demultiplexer
2-Line-to-4-Line Decoder or 1-Line-to-4-Line Demultiplexer
H
=
HIGH level
L
=
LOW level
X
=
don't care
Note 1: C
=
inputs C1 and C2 connected together
Note 2: G
=
inputs G1 and G2 connected together
Logic Diagram
Inputs
Outputs
Select
Strobe
(0)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Or Data
C (Note 1)
B
A
G (Note 2)
2Y0
2Y1
2Y2
2Y3
1Y0
1Y1
1Y2
1Y3
X
X
X
H
H
H
H
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
H
H
L
L
H
L
H
L
H
H
H
H
H
H
L
H
L
L
H
H
L
H
H
H
H
H
L
H
H
L
H
H
H
L
H
H
H
H
H
L
L
L
H
H
H
H
L
H
H
H
H
L
H
L
H
H
H
H
H
L
H
H
H
H
L
L
H
H
H
H
H
H
L
H
H
H
H
L
H
H
H
H
H
H
H
L
Inputs
Outputs
Select
Strobe
Data
1Y0
1Y1
1Y2
1Y3
B
A
G1
C1
X
X
H
X
H
H
H
H
L
L
L
H
L
H
H
H
L
H
L
H
H
L
H
H
H
L
L
H
H
H
L
H
H
H
L
H
H
H
H
L
X
X
X
L
H
H
H
H
Inputs
Outputs
Select
Strobe
Data
2Y0
2Y1
2Y2
2Y3
B
A
G2
C2
X
X
H
X
H
H
H
H
L
L
L
L
L
H
H
H
L
H
L
L
H
L
H
H
H
L
L
L
H
H
L
H
H
H
L
L
H
H
H
L
X
X
X
H
H
H
H
H
3
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DM74LS155
· D
M
74LS15
6
Absolute Maximum Ratings
(Note 3)
Note 3: 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.
DM74LS155 Recommended Operating Conditions
DM74LS155 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Note 4: All typicals are at V
CC
=
5V, T
A
=
25
°
C.
Note 5: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 6: I
CC
is measured with all outputs OPEN, A,B, and C1 inputs at 4.5V, and C2, G1, and G2 inputs GROUNDED.
DM74LS155 Switching Characteristics
at V
CC
=
5V and T
A
=
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
V
CC
Supply Voltage
4.75
5
5.25
V
V
IH
HIGH Level Input Voltage
2
V
V
IL
LOW Level Input Voltage
0.8
V
V
OH
HIGH Level Output Current
-
0.4
mA
I
OL
LOW Level Output Current
8
mA
T
A
Free Air Operating Temperature
0
70
°
C
Symbol
Parameter
Conditions
Min
Typ
Max
Units
(Note 4)
V
I
Input Clamp Voltage
V
CC
=
Min, I
I
=
-
18 mA
-
1.5
V
V
OH
HIGH Level
V
CC
=
Min, I
OH
=
Max
2.7
3.4
V
Output Voltage
V
IL
=
Max, V
IH
=
Min
V
OL
LOW
Level V
CC
=
Min, I
OL
=
Max
0.35
0.5
Output Voltage
V
IL
=
Max, V
IH
=
Min
V
I
OL
=
4 mA, V
CC
=
Min
0.25
0.4
I
I
Input Current @ Max Input Voltage
V
CC
=
Max, V
I
=
7V
0.1
mA
I
IH
HIGH Level Input Current
V
CC
=
Max, V
I
=
2.7V
20
µ
A
I
IL
LOW Level Input Current
V
CC
=
Max, V
I
=
0.4V
-
0.36
mA
I
OS
Short Circuit Output Current
V
CC
=
Max (Note 5)
-
20
-
100
mA
I
CC
Supply Current
V
CC
=
Max (Note 6)
6.1
10
mA
From (Input)
R
L
=
2 k
Symbol
Parameter
To (Output)
C
L
=
15 pF
C
L
=
50 pF
Units
Min
Max
Min
Max
t
PLH
Propagation Delay Time
A, B, C2, G1
18
22
ns
LOW-to-HIGH Level Output
or G2 to Y
t
PHL
Propagation Delay Time
A, B, C2, G1
27
35
ns
HIGH-to-LOW Level Output
or G2 to Y
t
PLH
Propagation Delay Time
A or B
18
24
ns
LOW-to-HIGH Level Output
to Y
t
PHL
Propagation Delay Time
A or B
27
35
ns
HIGH-to-LOW Level Output
to Y
t
PLH
Propagation Delay Time
C1
20
24
ns
LOW-to-HIGH Level Output
to Y
t
PHL
Propagation Delay Time
C1
27
35
ns
HIGH-to-LOW Level Output
to Y
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4
DM74LS155
· DM74LS156
DM74LS156 Recommended Operating Conditions
DM74LS156 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Note 7: All typicals are at V
CC
=
5V, T
A
=
25
°
C.
Note 8: I
CC
is measured with all outputs OPEN, A, B, and C1 inputs at 4.5V, and C2, G1, and G2 GROUNDED.
DM74LS156 Switching Characteristics
at V
CC
=
5V and T
A
=
25
°
C
Symbol
Parameter
Min
Nom
Max
Units
V
CC
Supply Voltage
4.75
5
5.25
V
V
IH
HIGH Level Input Voltage
2
V
V
IL
LOW Level Input Voltage
0.8
V
V
OH
HIGH Level Output Voltage
5.5
V
I
OL
LOW Level Output Current
8
mA
T
A
Free Air Operating Temperature
0
70
°
C
Symbol
Parameter
Conditions
Min
Typ
Max
Units
(Note 7)
V
I
Input Clamp Voltage
V
CC
=
Min, I
I
=
-
18 mA
-
1.5
V
I
CEX
HIGH Level
V
CC
=
Min, V
O
=
5.5V
100
µ
A
Output Current
V
IL
=
Max, V
IH
=
Min
V
OL
LOW
Level V
CC
=
Min, I
OL
=
Max
0.35
0.5
Output Voltage
V
IL
=
Max, V
IH
=
Min
V
I
OL
=
4 mA, V
CC
=
Min
0.25
0.4
I
I
Input Current @ Max Input Voltage
V
CC
=
Max, V
I
=
7V
0.1
mA
I
IH
HIGH Level Input Current
V
CC
=
Max, V
I
=
2.7V
20
µ
A
I
IL
LOW Level Input Current
V
CC
=
Max, V
I
=
0.4V
-
0.36
mA
I
CC
Supply Current
V
CC
=
Max (Note 8)
6.1
10
mA
From (Input)
R
L
=
2 k
Symbol
Parameter
To (Output)
C
L
=
15 pF
C
L
=
50 pF
Units
Min
Max
Min
Max
t
PLH
Propagation Delay Time
A, B, C2, G1
28
53
ns
LOW-to-HIGH Level Output
or G2 to Y
t
PHL
Propagation Delay Time
A, B, C2, G1
33
43
ns
HIGH-to-LOW Level Output
or G2 to Y
t
PLH
Propagation Delay Time
A or B
28
53
ns
LOW-to-HIGH Level Output
to Y
t
PHL
Propagation Delay Time
A or B
33
43
ns
HIGH-to-LOW Level Output
to Y
t
PLH
Propagation Delay Time
C1
28
53
ns
LOW-to-HIGH Level Output
to Y
t
PHL
Propagation Delay Time
C1
34
43
ns
HIGH-to-LOW Level Output
to Y
5
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DM74LS155
· D
M
74LS15
6
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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6
DM
74
LS155
· DM74LS156 D
u
a
l
2-Li
ne to 4-Li
ne Decoders/
Demult
ipl
exers
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.
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 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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