74Ls148d

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10-LINE-TO-4-LINE AND 8-LINE-TO-3-LINE PRIORITY ENCODERS
The SN54 / 74LS147 and the SN54/ 74LS148 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 zerocondition 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. The SN54 / 74LS748 is a proprietary Motorola part incorporating abuilt-in deglitcher network which minimizes glitches on the GS output. The glitch occurs on the negative going transition of the EI input when data inputs 0 – 7 are at logical ones. The only dc parameter differences between the LS148 and the LS748 are that (1) Pin 10 (input 0) has a fan-in of 2 on the LS748 versus a fan-in of 1 on the LS148; (2) Pins 1, 2, 3, 4, 11, 12 and 13 (inputs 1, 2, 3, 4, 5, 6,7) have a fan-in of 3 on the LS748 versus a fan-in of 2 on the LS148. The only ac difference is that tPHL from EI to EO is changed from 40 to 45 ns. SN54 / 74LS147 (TOP VIEW)
OUTPUT VCC 16 NC 15 D 14 D 4 5 1 4 2 5 6 3 6 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

SN54/74LS147 SN54/74LS148 SN54/74LS748

10-LINE-TO-4-LINE AND 8-LINE-TO-3-LINE PRIORITY ENCODERSLOW POWER SCHOTTKY

J SUFFIX CERAMIC CASE 620-09
16 1

16 1

N SUFFIX PLASTIC CASE 648-08

16 1

D SUFFIX SOIC CASE 751B-03

ORDERING INFORMATION
SN54LSXXXJ SN74LSXXXN SN74LSXXXD Ceramic Plastic SOIC

INPUTS

OUTPUTS

SN54 / 74LS148 SN54 / 74LS748 (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 A0A1 7 A1 8 GND OUTPUT A0 9

OUTPUTS

FAST AND LS TTL DATA 5-245

SN54/74LS147 • SN54/74LS148 • SN54/74LS748
SN54 / 74LS148 SN54 / 74LS748 FUNCTION TABLE
OUTPUTS 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 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 XX X X L H INPUTS 2 X H X X X X X L H H 3 X H X X X X L H H H 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

SN54 / 74LS147 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 HH 5 H X X X X L H H H H

H = HIGH Logic Level, L = LOW Logic Level, X = Irrelevant

FUNCTIONAL BLOCK DIAGRAMS

1

(11) 0

(10) (15) EO

(12) 2 (9) A 1

(11)

(14) GS

(13) 3 2

(12) (8) A0

(1) 4 (7) 5 (2) 3

(13)

B 4

(1)

(3) 6 5

(2)

(7) A1

7

(4)

(6) C

(3) 6

8

(5) 7

(4)

(6) A2

9

(10)

(14)

D

(5) EI

SN54 / 74LS147SN54 / 74LS148

FAST AND LS TTL DATA 5-246

SN54/74LS147 • SN54/74LS148 • SN54/74LS748
FUNCTIONAL BLOCK DIAGRAMS (continued)

G31

(10) 0

G13

(15) EO

(11) 1 G2 (12) 2 G3 (13) 3 G4 4 (1) G5 (2) 5 G6 (3) G7 (4) 7 G8 (5) EI G1 G28 G12 G11 G23 G10 G18 G9 G29

(14) GS

(9) A0

(7)

A1

6

(6) A2

SN54 / 74LS748

FAST AND LS TTL DATA 5-247

SN54/74LS147 • SN54/74LS148• SN54/74LS748
GUARANTEED OPERATING RANGES
Symbol VCC TA IOH IOL Supply Voltage Operating Ambient Temperature Range Output Current — High Output Current — Low Parameter 54 74 54 74 54, 74 54 74 Min 4.5 4.75 – 55 0 Typ 5.0 5.0 25 25 Max 5.5 5.25 125 70 – 0.4 4.0 8.0 Unit V °C mA mA

DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits Symbol VIH VIL VIK...
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