Lab 5

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 implieddecimal 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 VCC TA IOH IOL ParameterSupply 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 SN74LS148N SN74LS148D Package 16 Pin DIP 16 Pin 16 Pin DIP 16 Pin Shipping2000 Units/Box 2500/Tape & Reel 2000 Units/Box 2500/Tape & Reel

© Semiconductor Components Industries, LLC, 1999

1

December, 1999 – Rev. 6

Publication Order Number: SN74LS147/D

SN74LS147 SN74LS148
SN74LS147 (TOP VIEW)
OUTPUT VCC 16 NC 15 D 14 D 4 5 1 4 2 5 6 3 6 INPUTS 7 4 7 8 5 8 C 6 C B 7 B 8 GND 3 13 3 INPUTS 2 12 2 1 11 1 9 10 9 A OUTPUT A 9

OUTPUTS

SN74LS148 (TOP VIEW)OUTPUTS VCC 16 EO 15 EO 4 5 1 4 2 5 6 3 6 INPUTS 7 4 7 EI 5 E1 A2 6 A2 GS 14 GS 3 13 3 INPUTS 2 12 2 1 11 1 0 10 0 A0 A1 7 A1 8 GND OUTPUT A0 9

OUTPUTS

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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 LH 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 A1H 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

1

(11) 0 (12) (9) (13) 2 (1) 3 (2) (7) B 4 (3) 5 (4) (6) A 1

(10) (15) (11) (14) EO GS

2

3

(12) (8) (13) (1) (7) A0

4 5

6 7

(2)

A1

(3) C 6 (4) 7 (6)

8 9

(5) (10) (14)

A2

D(5) EI

SN74LS147

SN74LS148

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SN74LS147 SN74LS148
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits Symbol VIH VIL VIK VOH Parameter Input HIGH Voltage Input LOW Voltage Input Clamp Diode Voltage Output HIGH Voltage 2.7 – 0.65 3.5 0.25 VO OL Output LOW Voltage 0.35 Input HIGH Current All Others Inputs 1 – 7 (LS148) All OthersInputs 1 – 7 (LS148) IIL IOS ICCH ICCL Input LOW Current All Others Inputs 1 – 7 (LS148) Short Circuit Current (Note 1) Power Supply Current Output HIGH Output LOW – 20 0.5 20 40 0.1 0.2 – 0.4 – 0.8 – 100 17 20 V µA IOL = 8.0 mA 0.4 Min 2.0 0.8 – 1.5 Typ Max Unit V V V V V Test Conditions Guaranteed Input HIGH Voltage for All Inputs Guaranteed Input LOW Voltage for All Inputs VCC = MIN, IIN = – 18mA VCC = MIN, IOH = MAX, VIN = VIH or VIL per Truth Table IOL = 4.0 mA VCC = VCC MIN, VIN = VIL or VIH per Truth Table

VCC = MAX, VIN = 2.7 V

IIH

mA

VCC = MAX, VIN = 7.0 V

mA mA mA mA

VCC = MAX, VIN = 0.4 V VCC = MAX VCC = MAX, All Inputs = 4.5 V VCC = MAX, Inputs 7 & E1 = GND All Other Inputs = 4.5 V

Note 1: Not more than one output should be shorted at a time, nor for more...