© 1999 Fairchild Semiconductor Corporation DS009945 www.fairchildsemi.com
November 1988
Revised November 1999
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• 74ACT251 8-I
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Out
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74AC251 74ACT251
8-Input Multiplexer with 3-STATE Output
General Description
The AC/ACT251 is a high-speed 8-input digital multiplexer.
It provides, in one package, the ability to select one bit of
data from up to eight sources. It can be used as universal
function generator to generate any logic function of four
variables. Both true and complementary outputs are pro-
vided.
Features
a73 I
CC
reduced by 50%
a73 Multifunctional capability
a73 On-chip select logic decoding
a73 Inverting and noninverting 3-STATE outputs
a73 Outputs source/sink 24 mA
a73 ACT251 has TTL-compatible inputs

Ordering Code:
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Logic Symbols
IEEE/IEC
Connection Diagram
Pin Descriptions
FACT is a trademark of Fairchild Semiconductor Corporation.
Order Number Package Number Package Description
74AC251SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74AC251SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74AC251MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74AC251PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
74ACT251SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74ACT251MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74ACT251PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
Pin Names Description
S
0
–S
2
Select Inputs
OE 3-STATE Output Enable Input
I
0
–I
7
Multiplexer Inputs
Z 3-STATE Multiplexer Output
Z Complementary 3-STATE Multiplexer Output