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National Semiconductor |
www.DataSheet4U.com
September 1998
54AC521 • 54ACT521
8-Bit Identity Comparator
General Description
The AC/ACT521 is an expandable 8-bit comparator. It com-
pares two words of up to eight bits each and provides a LOW
output when the two words match bit for bit. The expansion
input IA = B also serves as an active LOW enable input.
Features
n ICC reduced by 50%
n Compares two 8-bit words in 6.5 ns typ
n Expandable to any word length
n Outputs source/sink 24 mA
n ACT521 has TTL-compatible inputs
n Standard microcircuit Drawing (SMD)
54AC521: 5962-90985
54ACT521: 5962-89793
Logic Symbols
Connection Diagram
Pin Assignment
for DIP and CERPACK
IEEE/IEC
DS100291-1
DS100291-2
Pin Assignment
for LCC
DS100291-4
DS100291-3
Pin Descriptions
Pin Names
A0–A7
B0–B7
TA = B
OA = B
Description
Word A Inputs
Word B Inputs
Expansion or Enable Input
Identity Output
FACT™ is a trademark of Fairchild Semiconductor Corporation.
© 1998 National Semiconductor Corporation DS100291
www.national.com
Truth Table
Inputs
IA = B
L
L
H
H
A, B
A = B (Note 1)
A≠B
A = B (Note 1)
A≠B
Note 1: A0 = B0, A1 = B1, A2 = B2, etc.
H = HIGH Voltage Level
L = LOW Voltage Level
Logic Diagram
Outputs
OA = B
L
H
H
H
DS100291-5
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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