SN74LS147, SN74LS148
10−Line−to−4−Line
and 8−Line−to−3−Line
Priority Encoders
The SN74LS147 and the SN74LS148 are Priority Encoders. They
provide priority decoding of the inputs to ensure that only the highest
order data line is encoded. Both devices have data inputs and outputs
which are active at the low logic level.
The LS147 encodes nine data lines to four-line (8-4-2-1) BCD. The
implied decimal zero condition does not require an input condition
because zero is encoded when all nine data lines are at a high logic
level.
The LS148 encodes eight data lines to three-line (4-2-1) binary
(octal). By providing cascading circuitry (Enable Input EI and Enable
Output EO) octal expansion is allowed without needing external
circuitry.
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
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LOW
POWER
SCHOTTKY
16
1
PLASTIC
N SUFFIX
CASE 648
16
1
SOIC
D SUFFIX
CASE 751B
ORDERING INFORMATION
Device
SN74LS147N
SN74LS147D
SN74LS147DR2
SN74LS148N
SN74LS148D
SN74LS148DR2
Package
16 Pin DIP
SOIC−16
SOIC−16
16 Pin DIP
SOIC−16
SOIC−16
Shipping
2000 Units/Box
38 Units/Rail
2500/Tape & Reel
2000 Units/Box
38 Units/Rail
2500/Tape & Reel
©
Semiconductor Components Industries, LLC, 2006
June, 2006
−
Rev. 8
1
Publication Order Number:
SN74LS147/D
SN74LS147, SN74LS148
SN74LS147
FUNCTION TABLE
INPUTS
1
H
X
X
X
X
X
X
X
X
L
2
H
X
X
X
X
X
X
X
L
H
3
H
X
X
X
X
X
X
L
H
H
4
H
X
X
X
X
X
L
H
H
H
5
H
X
X
X
X
L
H
H
H
H
6
H
X
X
X
L
H
H
H
H
H
7
H
X
X
L
H
H
H
H
H
H
8
H
X
L
H
H
H
H
H
H
H
9
H
L
H
H
H
H
H
H
H
H
D
H
L
L
H
H
H
H
H
H
H
OUTPUTS
C
H
H
H
L
L
L
L
H
H
H
B
H
H
H
L
L
H
H
L
L
H
A
H
L
H
L
H
L
H
L
H
L
EI
H
L
L
L
L
L
L
L
L
L
0
X
H
X
X
X
X
X
X
X
L
1
X
H
X
X
X
X
X
X
L
H
2
X
H
X
X
X
X
X
L
H
H
3
X
H
X
X
X
X
L
H
H
H
SN74LS148
FUNCTION TABLE
INPUTS
4
X
H
X
X
X
L
H
H
H
H
5
X
H
X
X
L
H
H
H
H
H
6
X
H
X
L
H
H
H
H
H
H
7
X
H
L
H
H
H
H
H
H
H
A2
H
H
L
L
L
L
H
H
H
H
OUTPUTS
A1
H
H
L
L
H
H
L
L
H
H
A0
H
H
L
H
L
H
L
H
L
H
GS
H
H
L
L
L
L
L
L
L
L
EO
H
L
H
H
H
H
H
H
H
H
H = HIGH Logic Level, L = LOW Logic Level, X = Irrelevant
FUNCTIONAL BLOCK DIAGRAMS
(11)
(12)
(13)
2
(1)
(2)
(3)
(4)
(5)
(10)
(14)
(7)
B
3
4
5
(6)
C
6
7
D
EI
(10)
(15)
(11)
(12)
(8)
(13)
(1)
(2)
(3)
(4)
(5)
(7)
A0
(14)
EO
GS
1
2
3
4
5
6
7
8
9
0
(9)
1
A
A1
(6)
A2
SN74LS147
SN74LS148
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3
SN74LS147, SN74LS148
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
0.35
0.4
0.5
20
40
0.1
0.2
−0.4
−0.8
−20
−100
17
20
Min
2.0
0.8
−1.5
Typ
Max
Unit
V
V
V
V
V
V
μA
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
I
OL
= 8.0 mA
V
CC
= V
CC
MIN,
V
IN
= V
IL
or V
IH
per Truth Table
V
OL
Output LOW Voltage
Input HIGH Current
All Others
Inputs 1
−7
(LS148)
All Others
Inputs 1
−7
(LS148)
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, All Inputs = 4.5 V
V
CC
= MAX, Inputs 7 & E1 = GND
All Other Inputs = 4.5 V
I
IH
mA
I
IL
I
OS
I
CCH
I
CCL
Input LOW Current
All Others
Inputs 1
−7
(LS148)
Short Circuit Current (Note 1)
Power Supply Current Output HIGH
Output LOW
mA
mA
mA
mA
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
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