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SN54/74LS42
ONE-OF-TEN DECODER
The LSTTL / MSI SN54 / 74LS42 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 Motorola TTL families.






ONE-OF-TEN DECODER

Multifunction Capability
Mutually ExclusiveOutputs
Demultiplexing Capability
Input Clamp Diodes Limit High Speed Termination Effects

LOW POWER SCHOTTKY

CONNECTION DIAGRAM DIP (TOP VIEW)
A0
15

VCC
16

A1
14

A2
13

A3
12

9

8

11

10

J SUFFIX
CERAMIC
CASE 620-09

7
9

16
1
NOTE:
The Flatpak version has the
same pinouts (Connection
Diagram) as the Dual In-Line
Package.

1

2

3

4

5

67

8

0

1

2

3

4

5

6

GND

N SUFFIX
PLASTIC
CASE 648-08

16
1

PIN NAMES

LOADING (Note a)
HIGH

A0 – A3
0 to 9

Address Inputs
Outputs, Active LOW (Note b)

D SUFFIX
SOIC
CASE 751B-03

LOW

0.5 U.L.
10 U.L.

16

0.25 U.L.
5(2.5) U.L.

1

NOTES:
a) 1 TTL Unit Load (U.L.) = 40 µA HIGH/1.6 mA LOW.
b) The Output LOW drive factor is 2.5U.L. for Military (54) and 5 U.L. for Commercial (74)
Temperature Ranges.

ORDERING INFORMATION
SN54LSXXJ
SN74LSXXN
SN74LSXXD

Ceramic
Plastic
SOIC

LOGIC DIAGRAM
A0

A1
15

A2

LOGIC SYMBOL

A3
13

14

12

15

14

13

12

A0

A1

A2

A3

0123456789

1

0

3

2

1

2

4

3

5

4

6

5

7

6

10

9

7

8

11

9VCC = PIN 16
GND = PIN 8
= PIN NUMBERS

FAST AND LS TTL DATA
5-1

1 2 3 4 5 6 7 9 10 11
VCC = PIN 16
GND = PIN 8

SN54/74LS42
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.
Thelogic 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 A3 produces a useful inhibit function when the LS42 is used as a one-of-eight decoder. The A3
input can also be used as the Data input in an 8-output
demultiplexer application.

TRUTH TABLE
A0

A1

A2

A3

0

1

2

3

4

56

7

8

9

L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H

L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H

L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H

L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H

L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H

H
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H

H
H
L
H
H
H
H
H
H
H
H
H
H
H
H
H

H
H
H
L
H
H
H
H
HH
H
H
H
H
H
H

H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
H

H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H

H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H

H
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H

H
H
H
H
H
H
H
H
L
H
H
H
H
H
H
H

H
H
H
H
H
H
H
H
H
L
H
H
H
H
H
H

H = HIGH Voltage Level
L = LOW Voltage Level

GUARANTEED OPERATING RANGESMin

Typ

Max

Unit

VCC

Symbol
Supply Voltage

Parameter
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

FAST AND LS TTL DATA
5-2

SN54/74LS42
DC CHARACTERISTICSOVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits
Symbol
S bl

Min

Parameter
P

VIH

Input Clamp Diode Voltage

VOH

Input HIGH Current
Input HIGH Current

IIL

Input LOW Current

IOS

Short Circuit Current (Note 1)

ICC

Power Supply Current

Guaranteed Input HIGH Voltage for
All Inputs
Guaranteed Input LOW Voltage for
p
g
All Inputs

V...
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