SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B JUNE 1982 REVISED NOVEMBER 1995
Copyright
1995, Texas Instruments Incorporated
1
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
Compare Two 8-Bit Words
Choice of Totem-Pole or Open-Collector
Outputs
SN74ALS518 and
ALS520 Have 20-k
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
TYPE
INPUT
PULLUP
OUTPUT FUNCTION
AND
TYPE
PULLUP
RESISTOR
AND
CONFIGURATION
SN74ALS518
Yes
P = Q open collector
ALS520
Yes
P = Q totem pole
SN74ALS521
No
P = Q totem pole
SN74ALS521 is identical to
ALS688.
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-k
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
OUTPUTS
DATA
P, Q
ENABLE
G
P = Q
P = Q
P = Q
L
H
L
P > Q
L
L
H
P < Q
L
L
H
X
H
L
H
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
G
P0
Q0
P1
Q1
P2
Q2
P3
Q3
GND
V
CC
P = Q / P = Q
Q7
P7
Q6
P6
Q5
P5
Q4
P4
SN54ALS520 . . . J PACKAGE
SN74ALS518, SN74ALS520,
SN74ALS521 . . . DW OR N PACKAGE
(TOP VIEW)
3
2 1 20 19
9 10 11 12 13
4
5
6
7
8
18
17
16
15
14
Q7
P7
Q6
P6
Q5
P1
Q1
P2
Q2
P3
SN54ALS520 . . . FK PACKAGE
(TOP VIEW)
Q0
P0
G
Q4
P5
P
= Q
Q3
GND
P4
V
CC
P = Q for SN74ALS518
P = Q for
ALS520 and SN74ALS521
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.
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B JUNE 1982 REVISED NOVEMBER 1995
2
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
logic symbols
COMP
G1
1
0
2
P0
4
P1
6
P2
8
P3
11
P4
13
P5
15
P6
7
17
P7
0
3
Q0
5
Q1
7
Q2
9
Q3
12
Q4
14
Q5
16
Q6
7
18
Q7
P = Q
19
G
1P=Q
P
Q
COMP
G1
1
0
2
P0
4
P1
6
P2
8
P3
11
P4
13
P5
15
P6
7
17
P7
0
3
Q0
5
Q1
7
Q2
9
Q3
12
Q4
14
Q5
16
Q6
7
18
Q7
19
1P=Q
G
ALS520
SN74ALS521
P
Q
P = Q
SN74ALS518
These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B JUNE 1982 REVISED NOVEMBER 1995
3
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
logic diagrams (positive logic)
19
17
18
15
16
13
14
11
12
8
9
6
7
4
5
2
3
1
P = Q
P7
Q7
P6
Q6
P5
Q5
P4
Q4
P3
Q3
P2
Q2
P1
Q1
P0
Q0
G
SN74ALS518
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B JUNE 1982 REVISED NOVEMBER 1995
4
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
logic diagrams (positive logic) (continued)
19
17
18
15
16
13
14
11
12
8
9
6
7
4
5
2
3
1
P = Q
P7
Q7
P6
Q6
P5
Q5
P4
Q4
P3
Q3
P2
Q2
P1
Q1
P0
Q0
G
ALS520
SN74ALS521
SN54ALS520, SN74ALS518, SN74ALS520, SN74ALS521
8-BIT IDENTITY COMPARATORS
SDAS224B JUNE 1982 REVISED NOVEMBER 1995
5
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, V
CC
7 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage, V
I
: Q inputs
V
CC
+ 0.5 V or 5.5 V, whichever is less
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
All other inputs
7 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-state output voltage
7 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
: SN74ALS518
0
C to 70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range
65
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
recommended operating conditions
SN74ALS518
UNIT
MIN
NOM
MAX
UNIT
VCC
Supply voltage
4.5
5
5.5
V
VIH
High-level input voltage
2
V
VIL
Low-level input voltage
0.8
V
VOH
High-level output voltage
5.5
V
IOL
Low-level output current
24
mA
TA
Operating free-air temperature
0
70
C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
SN74ALS518
UNIT
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VIK
VCC = 4.5 V,
II = 18 mA
1.5
V
IOH
VCC = 5.5 V,
VOH = 5.5 V
0.1
mA
VOL
VCC = 4 5 V
IOL = 12 mA
0.25
0.4
V
VOL
VCC = 4.5 V
IOL = 24 mA
0.35
0.5
V
II
Q inputs
VCC = 5 5 V
VI = 5.5 V
0.1
mA
II
All other inputs
VCC = 5.5 V
VI = 7 V
0.1
mA
I
Q inputs
VCC = 5 5 V
VI = 2 7 V
0.2
mA
IIH
All other inputs
VCC = 5.5 V,
VI = 2.7 V
20
A
I
Q inputs
VCC = 5 5 V
VI = 0 4 V
0.6
mA
IIL
All other inputs
VCC = 5.5 V,
VI = 0.4 V
0.1
mA
ICC
VCC = 5.5 V,
See Note 1
11
17
mA
All typical values are at VCC = 5 V, TA = 25
C.
NOTE 1: ICC is measured with G grounded, and P and Q at 4.5 V.
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