Document
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
Parameter
Min Typ Max Unit
VCC Supply Voltage TA Operating Ambient
Temperature Range
4.75 5.0 5.25
V
0 25 70 °C
IOH Output Current − High IOL Output Current − Low
− 0.4 8.0
mA mA
http://onsemi.com
LOW POWER SCHOTTKY
16 1 PLASTIC N SUFFIX CASE 648
16 1
SOIC D SUFFIX CASE 751B
ORDERING INFORMATION
Device
Package
Shipping
SN74LS147N
16 Pin DIP 2000 Units/Box
SN74LS147D
SOIC−16
38 Units/Rail
SN74LS147DR2
SOIC−16 2500/Tape & Reel
SN74LS148N
16 Pin DIP 2000 Units/Box
SN74LS148D
SOIC−16
38 Units/Rail
SN74LS148DR2
SOIC−16 2500/Tape & Reel
© Semiconductor Components Industries, LLC, 2006
June, 2006 − Rev. 8
1
Publication Order Number: SN74LS147/D
SN74LS147, SN74LS148
SN74LS147 (TOP VIEW)
OUTPUT
INPUTS
VCC NC D 3 2 1 16 15 14 13 12 11
OUTPUT
9A 10 9
D321 9 4A
5 6 7 8C B
1 2 3 4 56 78
4 5 6 7 8 C B GND
INPUTS
OUTPUTS
SN74LS148 (TOP VIEW)
OUTPUTS
INPUTS
VCC EO GS 3 2 1 16 15 14 13 12 11
OUTPUT 0 A0 10 9
EO GS 3 2 1 0 4 A0
5 6 7 EI A2 A1
1 2 3 4 56 78 4 5 6 7 E1 A2 A1 GND
INPUTS
OUTPUTS
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SN74LS147, SN74LS148
SN74LS147 FUNCTION TABLE
INPUTS
OUTPUTS
1 2 3 4 5 6 7 8 9DCBA
HHHHHHHHHHHHH XXXXXXXX L LHH L XXXXXXX L HLHHH XXXXXX LHHH L L L XXXXX LHHHH L L H XXXX LHHHHH LH L XXX LHHHHHH LHH XX LHHHHHHHHL L X LHHHHHHHHHL H LHHHHHHHHHHH L
H = HIGH Logic Level, L = LOW Logic Level, X = Irrelevant
SN74LS148 FUNCTION TABLE
INPUTS
OUTPUTS
EI 0 1 2 3 4 5 6 7 A2 A1 A0 GS
HXXXXXXXX L HHHHHHHH L XXXXXXXL L XXXXXXLH L XXXXX LHH L XXXX LHHH L XXX LHHHH L XX LHHHHH L X LHHHHHH L LHHHHHHH
H H L L L L H H H H
HH HH LL LH HL HH LL LH HL HH
H H L L L L L L L L
EO
H L H H H H H H H H
1 (11) 2 (12)
(13) 3 4 (1) 5 (2) 6 (3) 7 (4) 8 (5) 9 (10)
SN74LS147
FUNCTIONAL BLOCK DIAGRAMS
(9) A
(7) B (6)
C (14) D
0 (10) (11)
1 (12)
2 (13)
3 (1)
4 (2)
5 (3)
6 (4)
7 (5)
EI
SN74LS148
(15) EO
(14) GS (8) A0
(7) A1
(6) A2
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SN74LS147, SN74LS148
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Symbol VIH
Parameter Input HIGH Voltage
Limits Min Typ Max
2.0
Unit Test Conditions
V
Guaranteed Input HIGH Voltage for All Inputs
VIL Input LOW Voltage
0.8
V
Guaranteed Input LOW Voltage for All In.