Motorola MC74ACT521DW, MC74ACT521N, MC74AC521DW, MC74AC521N Datasheet
5-1
FACT DATA
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=BB7A7B6A6B5A5B4A4
I
A=BA0B0A1B1A2B2A3B3
GND
PIN NAMES
A0–A7 Word A Inputs
B0–B7Word 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
*A0=B0, A1=B1, A2=B2, etc.
8-BIT IDENTITY
COMPARATOR
N SUFFIX
CASE 738-03
PLASTIC
DW SUFFIX
CASE 751D-04
PLASTIC
LOGIC SYMBOL
B7A7B6A6B5A5B4A4B3A3B2A2B1A1B0A
0
I
A=B
O
A=B
MC74AC521 MC74ACT521
5-2
FACT DATA
Please note that this diagram is provided only for the understanding of logic
operations and should not be used to estimate propagation delays.
LOGIC DIAGRAM
A
0
B
0
A
1
B
1
A
2
B
2
A
3
B
3
A
4
B
4
A
5
B
5
A
6
B
6
A
7
B
7
I
A=B
O
A=B
MAXIMUM RATINGS*
Symbol Parameter Value Unit
V
CC
DC Supply Voltage (Referenced to GND) –0.5 to +7.0 V
V
in
DC Input Voltage (Referenced to GND) –0.5 to VCC +0.5 V
V
out
DC Output Voltage (Referenced to GND) –0.5 to VCC +0.5 V
I
in
DC Input Current, per Pin ±20 mA
I
out
DC Output Sink/Source Current, per Pin ±50 mA
I
CC
DC VCC or GND Current per Output Pin ±50 mA
T
stg
Storage Temperature –65 to +150 °C
* Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the Recommended
Operating Conditions.
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