SN74LS42
One-of-Ten Decoder
The LSTTL / MSI SN74LS42 is a Multipurpose Decoder designed
to accept four BCD inputs and provide ten mutually exclusive outputs.
The LS42 is fabricated with the Schottky barrier diode process for
high speed and is completely compatible with all ON Semiconductor
TTL families.
•
Multifunction Capability
•
Mutually Exclusive Outputs
•
Demultiplexing Capability
•
Input Clamp Diodes Limit High Speed Termination Effects
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LOW
POWER
SCHOTTKY
GUARANTEED OPERATING RANGES
Symbol
V
CC
T
A
I
OH
I
OL
Parameter
Supply Voltage
Operating Ambient
Temperature Range
Output Current – High
Output Current – Low
Min
4.75
0
Typ
5.0
25
Max
5.25
70
– 0.4
8.0
Unit
V
°C
mA
mA
16
1
PLASTIC
N SUFFIX
CASE 648
16
1
SOIC
D SUFFIX
CASE 751B
ORDERING INFORMATION
Device
SN74LS42N
SN74LS42D
Package
16 Pin DIP
16 Pin
Shipping
2000 Units/Box
2500/Tape & Reel
©
Semiconductor Components Industries, LLC, 1999
1
December, 1999 – Rev. 6
Publication Order Number:
SN74LS42/D
SN74LS42
CONNECTION DIAGRAM DIP
(TOP VIEW)
V
CC
16
A
0
15
A
1
14
A
2
13
A
3
12
9
11
8
10
7
9
NOTE:
The Flatpak version
has the same pinouts
(Connection Diagram)
as the Dual In-Line
Package.
1
0
2
1
3
2
4
3
5
4
6
5
7
6
8
GND
LOADING
(Note a)
PIN NAMES
A
0
– A
3
0 to 9
Address Inputs
Outputs, Active LOW
HIGH
0.5 U.L.
10 U.L.
LOW
0.25 U.L.
5 U.L.
NOTES:
a) 1 TTL Unit Load (U.L.) = 40
m
A HIGH/1.6 mA LOW.
LOGIC SYMBOL
15
14
13
12
A
0
A
1
A
2
A
3
0 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 9 10 11
V
CC
= PIN 16
GND = PIN 8
LOGIC DIAGRAM
A
0
15
A
1
14
A
2
13
A
3
12
1
2
3
4
5
6
7
9
10
11
0
1
2
3
4
5
6
7
8
9
V
CC
= PIN 16
GND = PIN 8
= PIN NUMBERS
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2
SN74LS42
FUNCTIONAL DESCRIPTION
The LS42 decoder accepts four active HIGH BCD inputs
and provides ten mutually exclusive active LOW outputs, as
shown by logic symbol or diagram. The active LOW outputs
facilitate addressing other MSI units with LOW input
enables.
The logic design of the LS42 ensures that all outputs
are HIGH when binary codes greater than nine are applied
to the inputs.
The most significant input A
3
produces a useful inhibit
function when the LS42 is used as a one-of-eight decoder.
The A
3
input can also be used as the Data input in an 8-output
demultiplexer application.
TRUTH TABLE
A
0
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
A
1
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
A
2
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
A
3
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
0
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
1
H
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
2
H
H
L
H
H
H
H
H
H
H
H
H
H
H
H
H
3
H
H
H
L
H
H
H
H
H
H
H
H
H
H
H
H
4
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
H
5
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
6
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
7
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
8
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
9
H
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H = HIGH Voltage Level
L = LOW Voltage Level
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3
SN74LS42
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Limits
Symbol
V
IH
V
IL
V
IK
V
OH
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Clamp Diode Voltage
Output HIGH Voltage
2.7
– 0.65
3.5
0.25
V
O
OL
Output LOW Voltage
0.35
I
IH
I
IL
I
OS
I
CC
Input HIGH Current
0.1
Input LOW Current
Short Circuit Current (Note 1)
Power Supply Current
– 20
– 0.4
–100
13
0.5
20
V
µA
mA
mA
mA
mA
I
OL
= 8.0 mA
0.4
Min
2.0
0.8
– 1.5
Typ
Max
Unit
V
V
V
V
V
Test Conditions
Guaranteed Input HIGH Voltage for
All Inputs
Guaranteed Input LOW Voltage for
All Inputs
V
CC
= MIN, I
IN
= – 18 mA
V
CC
= MIN, I
OH
= MAX, V
IN
= V
IH
or V
IL
per Truth Table
I
OL
= 4.0 mA
V
CC
= V
CC
MIN,
V
IN
= V
IL
or V
IH
per Truth Table
V
CC
= MAX, V
IN
= 2.7 V
V
CC
= MAX, V
IN
= 7.0 V
V
CC
= MAX, V
IN
= 0.4 V
V
CC
= MAX
V
CC
= MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(T
A
= 25°C)
Limits
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
Parameter
Propagation Delay
(2 Levels)
Propagation Delay
(3 Levels)
Min
Typ
15
15
20
20
Max
25
25
30
30
Unit
ns
ns
Test Conditions
Figure 2
Figure 1
V
CC
= 5.0 V
C
L
= 15 pF
AC WAVEFORMS
V
IN
1.3 V
t
PHL
1.3 V
t
PLH
1.3 V
1.3 V
V
IN
1.3 V
t
PHL
1.3 V
t
PLH
1.3 V
V
OUT
V
OUT
1.3 V
Figure 1.
Figure 2.
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4
SN74LS42
PACKAGE DIMENSIONS
N SUFFIX
PLASTIC PACKAGE
CASE 648–08
ISSUE R
–A–
16
9
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.
DIM
A
B
C
D
F
G
H
J
K
L
M
S
INCHES
MIN
MAX
0.740
0.770
0.250
0.270
0.145
0.175
0.015
0.021
0.040
0.70
0.100 BSC
0.050 BSC
0.008
0.015
0.110
0.130
0.295
0.305
0
_
10
_
0.020
0.040
MILLIMETERS
MIN
MAX
18.80
19.55
6.35
6.85
3.69
4.44
0.39
0.53
1.02
1.77
2.54 BSC
1.27 BSC
0.21
0.38
2.80
3.30
7.50
7.74
0
_
10
_
0.51
1.01
B
1
8
F
S
C
L
–T–
H
G
D
16 PL
SEATING
PLANE
K
J
T A
M
M
0.25 (0.010)
M
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5
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