5-53
FAST AND LS TTL DATA
ONE-OF-TEN DECODER
The LSTTL/MSI SN54/74LS42 is a Multipurpose Decoder designed to ac-
cept 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.
•Multifunction Capability
•Mutually Exclusive Outputs
•Demultiplexing Capability
•Input Clamp Diodes Limit High Speed Termination Effects
14 13 12 11 10 9
123456
VCC
7
16 15
8
A0A1A2A398 7
0 1 2 3 4 5 6 GND
NOTE:
The Flatpak version has the
same pinouts (Connection
Diagram) as the Dual In-Line
Package.
CONNECTION DIAGRAM DIP (TOP VIEW)
PIN NAMES LOADING (Note a)
HIGH LOW
A0 – A3
0 to 9 Address Inputs
Outputs, Active LOW (Note b) 0.5 U.L.
10 U.L. 0.25 U.L.
5(2.5) U.L.
NOTES:
a) 1 TTL Unit Load (U.L.) = 40 µA 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.
3
LOGIC DIAGRAM
14
4 5 10 11
121315
1 2 6 7 9
1 2 3 4 5 60
A0A1A2A3
987
VCC = PIN 16
GND = PIN 8
= PIN NUMBERS
SN54/74LS42
ONE-OF-TEN DECODER
LOW POWER SCHOTTKY
J SUFFIX
CERAMIC
CASE 620-09
N SUFFIX
PLASTIC
CASE 648-08
16 1
16
1
ORDERING INFORMATION
SN54LSXXJ Ceramic
SN74LSXXN Plastic
SN74LSXXD SOIC
16 1
D SUFFIX
SOIC
CASE 751B-03
LOGIC SYMBOL
VCC = PIN 16
GND = PIN 8
15 14 13 12
0 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 9 10 11
A0A1A2A3
5-54
FAST AND LS TTL DATA
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.
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 A3 produces a useful inhibit func-
tion 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
A0A1A2A30123456789
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
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
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 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
TAOperating Ambient Temperature Range 54
74 –55
025
25 125
70 °C
IOH Output Current — High 54, 74 –0.4 mA
IOL Output Current — Low 54
74 4.0
8.0 mA
5-55
FAST AND LS TTL DATA
SN54/74LS42
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
V
CC = 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 µA 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 13 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
Limits
Unit
Test Conditions
Symbol
Parameter
Min Typ Max
Unit
Test Conditions
tPLH
tPHL Propagation Delay
(2 Levels) 15
15 25
25 ns Figure 2
V
CC = 5.0 V
CL = 15 pF
tPLH
tPHL Propagation Delay
(3 Levels) 20
20 30
30 ns Figure 1
VCC = 5.0 V
CL = 15 pF
AC WAVEFORMS
VIN
VOUT
1.3 V 1.3 V
1.3 V 1.3 V
tPHL tPLH
Figure 1 Figure 2
1.3 V 1.3 V
1.3 V1.3 V
tPLH
tPHL
VIN
VOUT
