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ꢇ ꢋꢌ ꢍꢋ ꢎꢉ ꢏꢄꢐꢄꢉꢀ ꢑꢅ ꢑꢒꢐꢌ ꢓꢀꢔ ꢕꢖ ꢅꢐ ꢗꢘ ꢅꢑ ꢙꢑ ꢓ
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SDAS215A − APRIL 1982 − REVISED DECEMBER 1994
SN54ALS251 . . . J PACKAGE
SN74ALS251 . . . D OR N PACKAGE
(TOP VIEW)
• 3-State Version of the ′ALS151
• 3-State Outputs Interface Directly With
System Bus
• Perform Parallel-to-Serial Conversion
D3
D2
D1
D0
Y
W
OE
GND
V
CC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
• Complementary Outputs Provide True and
D4
D5
D6
D7
A
Inverted Data
• Package Options Include Plastic
Small-Outline (D) Packages, Ceramic Chip
Carriers (FK), and Standard Plastic (N) and
Ceramic (J) 300-mil DIPs
B
C
description
SN54ALS251 . . . FK PACKAGE
(TOP VIEW)
These data selectors/multiplexers contain full
binary decoding to select one-of-eight data
sources and feature controlled complementary
3-state outputs.
The 3-state outputs can interface with and drive
data lines of bus-organized systems. With all but
one of the common outputs disabled (at the
high-impedance state), the low impedance of the
signal-enabled output drives the bus line to a high
or low logic level. Both outputs are controlled by
the output-enable (OE) input. The outputs are
disabled when OE is high.
3
2
1
20 19
18 D5
D1
D0
NC
Y
4
5
6
7
8
17
16
15
14
D6
NC
D7
A
W
9 10 11 12 13
The SN54ALS251 is characterized for operation
over the full military temperature range of −55°C
to 125°C. The SN74ALS251 is characterized for
operation from 0°C to 70°C.
NC − No internal connection
FUNCTION TABLE
INPUTS
SELECT
OUTPUTS
OE
C
X
L
B
X
L
A
X
L
Y
W
Z
H
L
L
L
L
L
L
L
L
Z
D0
D1
D2
D3
D4
D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
L
L
H
L
L
H
H
L
L
H
L
H
H
H
H
L
H
L
H
H
H
D0, D1, . . . D7 = the level of the respective D input
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Copyright 1994, Texas Instruments Incorporated
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1
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