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ONE-OF-TEN DECODER. SN54LS42 Datasheet |
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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
CONNECTION DIAGRAM DIP (TOP VIEW)
VCC A0 A1 A2 A3 9 8 7
16 15 14 13 12 11 10 9
NOTE:
The Flatpak version has the
same pinouts (Connection
Diagram) as the Dual In-Line
Package.
12
01
3 4 56
2 3 45
78
6 GND
PIN NAMES
A0 – A3
0 to 9
Address Inputs
Outputs, Active LOW (Note b)
LOADING (Note a)
HIGH
LOW
0.5 U.L.
0.25 U.L.
10 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.
A0
15
LOGIC DIAGRAM
A1
14
A2
13
A3
12
12
3 45
6
7 9 10 11
0 1 2 3 4 56 7 89
VCC = PIN 16
GND = PIN 8
= PIN NUMBERS
FAST AND LS TTL DATA
5-53
SN54/74LS42
ONE-OF-TEN DECODER
LOW POWER SCHOTTKY
16
1
J SUFFIX
CERAMIC
CASE 620-09
16
1
N SUFFIX
PLASTIC
CASE 648-08
16
1
D SUFFIX
SOIC
CASE 751B-03
ORDERING INFORMATION
SN54LSXXJ
SN74LSXXN
SN74LSXXD
Ceramic
Plastic
SOIC
LOGIC SYMBOL
15 14 13 12
A0 A1 A2 A3
012345 6 7 89
1 2 3 4 5 6 7 9 10 11
VCC = PIN 16
GND = PIN 8
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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
A0 A1 A2 A3 0 1 2 3 4 5 6 7 8 9
L L L L LHHHHHHHHH
H L L L HLHHHHHHHH
L H L L HHLHHHHHHH
H H L L HHHLHHHHHH
L L H L HHHHLHHHHH
H L H L HHHHHLHHHH
L H H L HHHHHHLHHH
H H H L HHHHHHHLHH
L L L H HHHHHHHHLH
H L L H HHHHHHHHHL
L H L H HHHHHHHHHH
H H L H HHHHHHHHHH
L L H H HHHHHHHHHH
H L H H HHHHHHHHHH
L H H H HHHHHHHHHH
H H H H HHHHHHHHHH
H = HIGH Voltage Level
L = LOW Voltage Level
GUARANTEED OPERATING RANGES
Symbol
Parameter
VCC
Supply Voltage
TA Operating Ambient Temperature Range
IOH Output Current — High
IOL Output Current — Low
Min Typ Max Unit
54 4.5 5.0 5.5
74 4.75 5.0 5.25
V
54 – 55 25 125 °C
74 0 25 70
54, 74
– 0.4
mA
54 4.0 mA
74 8.0
FAST AND LS TTL DATA
5-54
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SN54 / 74LS42
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits
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
74
0.7 Guaranteed Input LOW Voltage for
0.8 V All Inputs
VIK
VOH
Input Clamp Diode Voltage
Output HIGH Voltage
54
74
– 0.65
– 1.5
2.5 3.5
2.7 3.5
V VCC = MIN, IIN = – 18 mA
V VCC = MIN, IOH = MAX, VIN = VIH
V or VIL per Truth Table
VOL
Output LOW Voltage
54, 74
74
0.25 0.4
0.35 0.5
V IOL = 4.0 mA VCC = VCC MIN,
VIN = VIL or VIH
V IOL = 8.0 mA per Truth Table
IIH Input HIGH Current
20
0.1
IIL Input LOW Current
IOS Short Circuit Current (Note 1)
– 20
ICC Power Supply Current
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
– 0.4
–100
13
µA VCC = MAX, VIN = 2.7 V
mA VCC = MAX, VIN = 7.0 V
mA VCC = MAX, VIN = 0.4 V
mA VCC = MAX
mA VCC = MAX
AC CHARACTERISTICS (TA = 25°C)
Symbol
tPLH
tPHL
tPLH
tPHL
Parameter
Propagation Delay
(2 Levels)
Propagation Delay
(3 Levels)
Limits
Min Typ Max
15 25
15 25
20 30
20 30
Unit Test Conditions
ns Figure 2
ns Figure 1
VCC = 5.0 V
CL = 15 pF
AC WAVEFORMS
VIN
VOUT
1.3 V
tPHL
1.3 V
1.3 V
tPLH
1.3 V
Figure 1
VIN
VOUT
1.3 V
tPHL
1.3 V
1.3 V
tPLH
1.3 V
Figure 2
FAST AND LS TTL DATA
5-55
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