5-230
FAST AND LS TTL DATA
1-OF-8 DECODER/
DEMULTIPLEXER
The LSTTL / MSI SN54 / 74LS138 is a high speed 1-of-8 Decoder /
Demultiplexer. This device is ideally suited for high speed bipolar memory
chip select address decoding. The multiple input enables allow parallel ex-
pansion to a 1-of-24 decoder using just three LS138 devices or to a 1-of-32
decoder using four LS138s and one inverter. The LS138 is fabricated with the
Schottky barrier diode process for high speed and is completely compatible
with all Motorola TTL families.
Demultiplexing Capability
Multiple Input Enable for Easy Expansion
Typical Power Dissipation of 32 mW
Active Low Mutually Exclusive Outputs
Input Clamp Diodes Limit High Speed Termination Effects
14
13
12
11
10
9
1
2
3
4
5
6
7
16
15
8
VCC
A0
O0
O1
O2
O3
O5
O4
O6
A1
A2
E1
E2
E3
O7 GND
CONNECTION DIAGRAM DIP (TOP VIEW)
NOTE:
The Flatpak version
has the same pinouts
(Connection Diagram) as
the Dual In-Line Package.
PIN NAMES
LOADING (Note a)
HIGH
LOW
A0 A2
E1, E2
E3
O0 O7
Address Inputs
Enable (Active LOW) Inputs
Enable (Active HIGH) Input
Active LOW Outputs (Note b)
0.5 U.L.
0.5 U.L.
0.5 U.L.
10 U.L.
0.25 U.L.
0.25 U.L.
0.25 U.L.
5 (2.5) U.L.
NOTES:
a) 1 TTL Unit Load (U.L.) = 40
A HIGH/1.6 mA LOW.
b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)
Temperature Ranges.
SN54/74LS138
1-OF-8 DECODER/
DEMULTIPLEXER
LOW POWER SCHOTTKY
J SUFFIX
CERAMIC
CASE 620-09
N SUFFIX
PLASTIC
CASE 648-08
16
1
16
1
ORDERING INFORMATION
SN54LSXXXJ
Ceramic
SN74LSXXXN
Plastic
SN74LSXXXD
SOIC
16
1
D SUFFIX
SOIC
CASE 751B-03
LOGIC SYMBOL
VCC = PIN 16
GND = PIN 8
15 14 13 12 11 10 9
1 2 3
4 5 6
1 2 3
A0 A1 A2
E
O0 O1 O2 O3 O4 O5 O6 O7
7
LOGIC DIAGRAM
A2
A1
A0
E1 E2 E3
O7
O6
O5
O4
O3
O2
O1
O0
VCC = PIN 16
GND = PIN 8
= PIN NUMBERS
3
2
1
4
5
6
7
9
15
14
13
12
11
10
5-231
FAST AND LS TTL DATA
SN54/74LS138
FUNCTIONAL DESCRIPTION
The LS138 is a high speed 1-of-8 Decoder/Demultiplexer
fabricated with the low power Schottky barrier diode process.
The decoder accepts three binary weighted inputs (A0, A1, A2)
and when enabled provides eight mutually exclusive active
LOW Outputs (O0O7). The LS138 features three Enable in-
puts, two active LOW (E1, E2) and one active HIGH (E3). All
outputs will be HIGH unless E1 and E2 are LOW and E3 is
HIGH. This multiple enable function allows easy parallel ex-
pansion of the device to a 1-of-32 (5 lines to 32 lines) decoder
with just four LS138s and one inverter. (See Figure a.)
The LS138 can be used as an 8-output demultiplexer by
using one of the active LOW Enable inputs as the data input
and the other Enable inputs as strobes. The Enable inputs
which are not used must be permanently tied to their appropri-
ate active HIGH or active LOW state.
TRUTH TABLE
INPUTS
OUTPUTS
E1
E2
E3
A0
A1
A2
O0
O1
O2
O3
O4
O5
O6
O7
H
X
X
X
X
X
H
H
H
H
H
H
H
H
X
H
X
X
X
X
H
H
H
H
H
H
H
H
X
X
L
X
X
X
H
H
H
H
H
H
H
H
L
L
H
L
L
L
L
H
H
H
H
H
H
H
L
L
H
H
L
L
H
L
H
H
H
H
H
H
L
L
H
L
H
L
H
H
L
H
H
H
H
H
L
L
H
H
H
L
H
H
H
L
H
H
H
H
L
L
H
L
L
H
H
H
H
H
L
H
H
H
L
L
H
H
L
H
H
H
H
H
H
L
H
H
L
L
H
L
H
H
H
H
H
H
H
H
L
H
L
L
H
H
H
H
H
H
H
H
H
H
H
L
H = HIGH Voltage Level
L = LOW Voltage Level
X = Don't Care
O0
O31
A0
A1
A2
A3
A4
H
LS04
A0 A1 A2
E
LS138
O0 O1 O2 O3 O4 O5 O6 O7
A0 A1 A2
E
LS138
O0 O1 O2 O3
O5 O6 O7
O4
O0 O1 O2 O3
O5 O6 O7
O4
E
LS138
A0 A1 A2
A0 A1 A2
E
LS138
O0
O2 O3
O5 O6 O7
O4
O1
1 2 3
1 2 3
1 2 3
1 2 3
Figure a
5-232
FAST AND LS TTL DATA
SN54/74LS138
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
VCC
Supply Voltage
54
74
4.5
4.75
5.0
5.0
5.5
5.25
V
TA
Operating Ambient Temperature Range
54
74
55
0
25
25
125
70
C
IOH
Output Current -- High
54, 74
0.4
mA
IOL
Output Current -- Low
54
74
4.0
8.0
mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
VIH
Input HIGH Voltage
2.0
V
Guaranteed Input HIGH Voltage for
All Inputs
VIL
Input LOW Voltage
54
0.7
V
Guaranteed Input LOW Voltage for
All Inputs
VIL
Input LOW Voltage
74
0.8
V
Guaranteed Input LOW Voltage for
All Inputs
VIK
Input Clamp Diode Voltage
0.65
1.5
V
VCC = MIN, IIN = 18 mA
VOH
Output HIGH Voltage
54
2.5
3.5
V
VCC = MIN, IOH = MAX, VIN = VIH
or VIL per Truth Table
VOH
Output HIGH Voltage
54
2.5
3.5
V
VCC = MIN, IOH = MAX, VIN = VIH
or VIL per Truth Table
VOH
Output HIGH Voltage
74
2.7
3.5
V
VCC = MIN, IOH = MAX, VIN = VIH
or VIL per Truth Table
VOL
Output LOW Voltage
54, 74
0.25
0.4
V
IOL = 4.0 mA
VCC = VCC MIN,
VIN = VIL or VIH
per Truth Table
VOL
Output LOW Voltage
74
0.35
0.5
V
IOL = 8.0 mA
VIN = VIL or VIH
per Truth Table
IIH
Input HIGH Current
20
A
VCC = MAX, VIN = 2.7 V
IIH
Input HIGH Current
0.1
mA
VCC = MAX, VIN = 7.0 V
IIL
Input LOW Current
0.4
mA
VCC = MAX, VIN = 0.4 V
IOS
Short Circuit Current (Note 1)
20
100
mA
VCC = MAX
ICC
Power Supply Current
10
mA
VCC = MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(TA = 25
C)
Symbol
Parameter
Levels of
Delay
Limits
Unit
Test Conditions
Symbol
Parameter
Levels of
Delay
Min
Typ
Max
Unit
Test Conditions
tPLH
tPHL
Propagation Delay
Address to Output
2
2
13
27
20
41
ns
VCC = 5.0 V
CL = 15 pF
tPLH
tPHL
Propagation Delay
Address to Output
3
3
18
26
27
39
ns
VCC = 5.0 V
CL = 15 pF
tPLH
tPHL
Propagation Delay E1 or E2
Enable to Output
2
2
12
21
18
32
ns
VCC = 5.0 V
CL = 15 pF
tPLH
tPHL
Propagation Delay E3
Enable to Output
3
3
17
25
26
38
ns
AC WAVEFORMS
Figure 1
Figure 2
VIN
VOUT
1.3 V
tPHL
1.3 V
1.3 V
1.3 V
tPLH
VIN
VOUT
1.3 V
tPHL
1.3 V
tPLH
1.3 V
1.3 V
5-233
FAST AND LS TTL DATA
MIN
MIN
MAX
MAX
MILLIMETERS
INCHES
DIM
A
B
C
D
F
G
J
K
M
P
R
9.80
3.80
1.35
0.35
0.40
0.19
0.10
0
5.80
0.25
10.00
4.00
1.75
0.49
1.25
0.25
0.25
7
6.20
0.50
0.386
0.150
0.054
0.014
0.016
0.008
0.004
0
0.229
0.010
0.393
0.157
0.068
0.019
0.049
0.009
0.009
7
0.244
0.019
1.27 BSC
0.050 BSC
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B DO NOT INCLUDE MOLD
PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. 751B 01 IS OBSOLETE, NEW STANDARD
751B 03.
1
8
9
16
-A-
-B-
P
16 PL
D
-T-
K
C
G
M
R X 45
F
J
8 PL
SEATING
PLANE
Case 751B-03 D Suffix
16-Pin Plastic
SO-16
B
0.25 (0.010)
M
M
T
0.25 (0.010)
B
A
M
S
S
Case 648-08 N Suffix
16-Pin Plastic
MIN
MIN
MAX
MAX
MILLIMETERS
INCHES
DIM
A
B
C
D
F
G
H
J
K
L
M
S
18.80
6.35
3.69
0.39
1.02
0.21
2.80
7.50
0
0.51
19.55
6.85
4.44
0.53
1.77
0.38
3.30
7.74
10
1.01
0.740
0.250
0.145
0.015
0.040
0.008
0.110
0.295
0
0.020
0.770
0.270
0.175
0.021
0.070
0.015
0.130
0.305
10
0.040
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L" TO CENTER OF LEADS WHEN
FORMED PARALLEL.
4. DIMENSION B" DOES NOT INCLUDE MOLD
FLASH.
5. ROUNDED CORNERS OPTIONAL.
6. 648 01 THRU 07 OBSOLETE, NEW STANDARD
648 08.
2.54 BSC
1.27 BSC
0.100 BSC
0.050 BSC
-A-
B
1
8
9
16
F
H
G
D
16 PL
S
C
-T-
SEATING
PLANE
K
J
M
L
T A
0.25 (0.010)
M
M
Case 620-09 J Suffix
16-Pin Ceramic Dual In-Line
MIN
MIN
MAX
MAX
MILLIMETERS
INCHES
DIM
19.05
6.10
0.39
1.40
0.23
0
0.39
19.55
7.36
4.19
0.53
1.77
0.27
5.08
15
0.88
0.750
0.240
0.015
0.055
0.009
0
0.015
0.770
0.290
0.165
0.021
0.070
0.011
0.200
15
0.035
1.27 BSC
2.54 BSC
7.62 BSC
0.050 BSC
0.100 BSC
0.300 BSC
A
B
C
D
E
F
G
J
K
L
M
N
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIM F MAY NARROW TO 0.76 (0.030) WHERE
THE LEAD ENTERS THE CERAMIC BODY.
5. 620 01 THRU 08 OBSOLETE, NEW STANDARD
620 09.
-B-
-A-
16 PL
-T-
C
D
E
F
G
J
K
M
N
SEATING
PLANE
16 PL
L
16
9
1
8
0.25 (0.010)
T A
M
S
0.25 (0.010)
T B
M
S
5-234
FAST AND LS TTL DATA
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the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit,
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