© 2005 Fairchild Semiconductor Corporation DS009964 www.fairchildsemi.com
November 1988
Revised March 2005
74AC521 • 74ACT521 8-Bit Identity Comparator
74AC521 • 74ACT521
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 I
A B
also serves as an active LOW enable
input.
Features
■ I
CC
reduced by 50%
■ 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
Ordering Code:
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering table.
Pb-Free package per JEDEC J-STD-020B.
Logic Symbols
IEEE/IEC
Connection Diagram
Pin Descriptions
FACT is a trademark of Fairchild Semiconductor Corporation.
Order Number Package Number Package Description
74AC521SC M20B 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide
74AC521SJ M20D Pb-Free 20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74AC521MTC MTC20 20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74AC521PC N20A 20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
74ACT521SC M20B 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide
74ACT521SJ M20D Pb-Free 20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74ACT521MTC MTC20 20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74ACT521PC N20A 20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Pin Names Description
A
0
–A
7
Word A Inputs
B
0
–B
7
Word B Inputs
T
A B
Expansion or Enable Input
O
A B
Identity Output
