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SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B – JUNE 1982 – REVISED NOVEMBER 1995
•
•
•
•
Compare Two 8-Bit Words
Choice of Totem-Pole or Open-Collector
Outputs
SN74ALS518 and
′ALS520
Have 20-kΩ
Pullup Resistors on Q Inputs
Package Options Include Plastic
Small-Outline (DW) Packages, Ceramic
Chip Carriers (FK), and Standard Plastic (N)
and Ceramic (J) 300-mil DIPs
INPUT
PULLUP
RESISTOR
Yes
Yes
OUTPUT FUNCTION
AND
CONFIGURATION
P = Q open collector
P = Q totem pole
SN54ALS520 . . . J PACKAGE
SN74ALS518, SN74ALS520,
SN74ALS521
. . .
DW OR N PACKAGE
(TOP VIEW)
TYPE
SN74ALS518
′ALS520
G
P0
Q0
P1
Q1
P2
Q2
P3
Q3
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CC
P = Q / P = Q
†
Q7
P7
Q6
P6
Q5
P5
Q4
P4
SN74ALS521‡
No
P = Q totem pole
‡ SN74ALS521 is identical to
′ALS688.
† P = Q for SN74ALS518
P = Q for
′ALS520
and SN74ALS521
SN54ALS520 . . . FK PACKAGE
(TOP VIEW)
description
These identity comparators perform comparisons
on two 8-bit binary or BCD words. The
SN74ALS518 provides P = Q outputs, while the
′ALS520
and SN74ALS521 provide P = Q
outputs. The SN74ALS518 has an open-collector
output. The SN74ALS518 and
′ALS520
feature
20-kΩ pullup resistors on the Q inputs for analog
or switch data.
The SN54ALS520 is characterized for operation
over the full military temperature range of – 55°C
to 125°C. The SN74ALS518, SN74ALS520, and
SN74ALS521 are characterized for operation
from 0°C to 70°C.
FUNCTION TABLE
INPUTS
DATA
P, Q
P=Q
P>Q
P<Q
X
ENABLE
G
L
L
L
H
OUTPUTS
P=Q
H
L
L
L
P=Q
L
H
H
H
P1
Q1
P2
Q2
P3
3
4
5
6
7
8
2 1 20 19
18
17
16
15
P=Q
Q7
P7
Q6
P6
Q5
14
9 10 11 12 13
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Copyright
©
1995, Texas Instruments Incorporated
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
Q3
GND
P4
Q4
P5
G
V
CC
Q0
P0
1
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B – JUNE 1982 – REVISED NOVEMBER 1995
logic symbols
†
SN74ALS518
1
G
P0
P1
P2
P3
P4
P5
P6
P7
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
2
4
6
8
11
13
15
17
3
5
7
9
12
14
16
18
7
Q
7
0
1P=Q
19
P=Q
P
COMP
G1
0
G
P0
P1
P2
P3
P4
P5
P6
P7
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
1
2
4
6
8
11
13
15
17
3
5
7
9
12
14
16
18
7
Q
7
0
1P=Q
19
P=Q
P
′ALS520
SN74ALS521
COMP
G1
0
† These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
2
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B – JUNE 1982 – REVISED NOVEMBER 1995
logic diagrams (positive logic)
SN74ALS518
P7
Q7
P6
Q6
P5
Q5
P4
Q4
P3
Q3
17
18
15
16
13
14
11
12
19
8
9
P=Q
P2
Q2
P1
Q1
P0
Q0
G
6
7
4
5
2
3
1
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
3
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B – JUNE 1982 – REVISED NOVEMBER 1995
logic diagrams (positive logic) (continued)
′ALS520
SN74ALS521
P7
Q7
P6
Q6
P5
Q5
P4
Q4
P3
Q3
17
18
15
16
13
14
11
12
19
8
9
P=Q
P2
Q2
P1
Q1
P0
Q0
G
6
7
4
5
2
3
1
4
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
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