5-1
FACT DATA
C0056C0262C0066C0105C0116 C0073C0100C0101C0110C0116C0105C0116C0121 C0067C0111C0109C0112C0097C0114C0097C0116C0111C0114
The MC74AC521/74ACT521 is an expandable 8-bit comparator. It
compares two words of up to eight bits each and provides a LOW output when
the two words match bit for bit. The expansion input I
A=B
also serves as an
active LOW enable input.
• Compares Two 8-Bit Words in 6.5 ns Typ
• Expandable to Any Word Length
• 20-Pin Package
• Outputs Source/Sink 24 mA
• ′ACT521 has TTL-Compatible Inputs
1920 18 17 16 15 14
21 3 4 5 6 7
V
CC
13
8
12
9
11
10
O
A=B
B
7
A
7
B
6
A
6
B
5
A
5
B
4
A
4
I
A=B
A
0
B
0
A
1
B
1
A
2
B
2
A
3
B
3
GND
PIN NAMES
A
0
–A
7
Word A Inputs
B
0
–B
7
Word B Inputs
I
A=B
Expansion or Enable Input
O
A=B
Identity Output
TRUTH TABLE
Inputs Outputs
I
A=B
A, B O
A=B
L A = B* L
L A ≠ B H
H A = B* H
H A ≠ B H
H = HIGH Voltage Level
L = LOW Voltage Level
*A
0
=B
0
, A
1
=B
1
, A
2
=B
2
, etc.
8-BIT IDENTITY
COMPARATOR
N SUFFIX
CASE 738-03
PLASTIC
DW SUFFIX
CASE 751D-04
PLASTIC
C0077C0067C0055C0052C0065C0067C0053C0050C0049
C0077C0067C0055C0052C0065C0067C0084C0053C0050C0049
LOGIC SYMBOL
B
7
A
7
B
6
A
6
B
5
A
5
B
4
A
4
B
3
A
3
B
2
A
2
B
1
A
1
B
0
A
0
I
A=B
O
A=B