SN54LS147 Datasheet, PDF (1/7 Pages) Motorola, Inc – 10-LINE-TO-4-LINE AND 8-LINE-TO-3-LINE PRIORITY ENCODERS

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 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.
The SN54 / 74LS748 is a proprietary Motorola part incorporating a built-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
INPUTS
OUTPUT
VCC NC D
3
2
1
9A
16 15 14 13 12 11 10 9
D
32
1
9
4
A
5
678C
B
1
2
3
4
56
78
4
56
7
8 C B GND
INPUTS
OUTPUTS
SN54 / 74LS148
SN54 / 74LS748
(TOP VIEW)
OUTPUTS
VCC EO GS 3
16 15 14 13
INPUTS
2
1
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
5
6
78
4
5
6
7 E1 A2 A1 GND
INPUTS
OUTPUTS
FAST AND LS TTL DATA
5-245
SN54/74LS147
SN54/74LS148
SN54/74LS748
10-LINE-TO-4-LINE
AND 8-LINE-TO-3-LINE
PRIORITY ENCODERS
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
SN54LSXXXJ Ceramic
SN74LSXXXN Plastic
SN74LSXXXD SOIC