2000 Fairchild Semiconductor Corporation
DS006214
www.fairchildsemi.com
April 1984
Revised April 2000
DM74ALS251 3-
ST
A
T
E 1-of
-8 Lin
e
Dat
a
Sel
ect
or/
M
ul
ti
pl
exer
DM74ALS251
3-STATE 1-of-8 Line Data Selector/Multiplexer
General Description
This Data Selector/Multiplexer contains full on-chip decod-
ing to select one-of-eight data sources as a result of a
unique three-bit binary code at the Select inputs. Two com-
plementary outputs provide both inverting and non-invert-
ing buffer operation. An Output Control input is provided
which, when at the high level, places both outputs in the
high impedance OFF-State. In order to prevent bus access
conflicts, output disable times are shorter than output
enable times. The Select input buffers incorporate internal
overlap features to ensure that select input changes do not
cause invalid output transients.
Features
s
Advanced oxide-isolated, ion-implanted Schottky TTL
process
s
Switching performance is guaranteed over full tempera-
ture and V
CC
supply range
s
Pin and functional compatible with LS family counterpart
s
Improved output transient handling capability
s
Output control circuitry incorporates power-up 3-STATE
feature
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Connection Diagram
Function Table
H
=
HIGH Level
L
=
LOW Level
X
=
Don't Care
Z
=
High Impedance (OFF)
D0 thru D7
=
The Level of the Respective D Input
Order Number
Package Number
Package Description
DM74ALS251M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74ALS251SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74ALS251N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Inputs
Outputs
Select
Strobe
C
B
A
S
Y
W
X
X
X
H
Z
Z
L
L
L
L
D
0
D
0
L
L
H
L
D
1
D
1
L
H
L
L
D
2
D
2
L
H
H
L
D
3
D
3
H
L
L
L
D
4
D
4
H
L
H
L
D
5
D
5
H
H
L
L
D
6
D
6
H
H
H
L
D
7
D
7
3
www.fairchildsemi.com
DM74ALS251
Absolute Maximum Ratings
(Note 1)
Note 1: The "Absolute Maximum Ratings" are those values beyond which
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the Electrical
Characteristics tables are not guaranteed at the absolute maximum ratings.
The "Recommended Operating Conditions" table will define the conditions
for actual device operation.
Recommended Operating Conditions
Electrical Characteristics
over recommended operating free air temperature range. All typical values are measured at V
CC
=
5V, T
A
=
25
C.
Supply Voltage, V
CC
7V
Input Voltage
7V
Voltage Applied to Disabled Output
5.5V
Operating Free Air Temperature Range
0
C to
+
70
C
Storage Temperature Range
-
65
C to
+
150
C
Typical
JA
N Package
78.0
C/W
M Package
107.0
C/W
Symbol
Parameter
Min
Nom
Max
Units
V
CC
Supply Voltage
4.5
5
5.5
V
V
IH
HIGH Level Input Voltage
2
V
V
IL
LOW Level Input Voltage
0.8
V
I
OH
HIGH Level Output Current
-
2.6
mA
I
OL
LOW Level Output Current
24
mA
T
A
Free Air Operating Temperature
0
70
C
Symbol
Parameter
Conditions
Min
Typ
Max
Units
V
IK
Input Clamp Voltage
V
CC
=
4.5V, I
IN
=
-
18 mA
-
1.5
V
V
OH
HIGH Level
V
CC
=
4.5V, I
OH
=
Max
2.4
3.2
V
Output Voltage
I
OH
=
-
400
A, V
CC
=
4.5V to 5.5V
V
CC
-
2
V
V
OL
LOW Level
V
CC
=
4.5V
I
OL
=
24 mA
0.35
0.5
V
Output Voltage
I
I
Input Current at Maximum
V
CC
=
5.5V, V
IH
=
7V
0.1
mA
Input Voltage
I
IH
HIGH Level Input Current
V
CC
=
5.5V, V
IH
=
2.7V
20
A
I
IL
LOW Level Input Current
V
CC
=
5.5V, V
IN
=
0.4V
-
0.1
mA
I
O
Output Drive Current
V
CC
=
5.5V, V
OUT
=
2.25V
-
30
-
112
mA
I
OZH
OFF-State Output
V
CC
=
5.5V, V
OUT
=
2.7V
20
A
Current, HIGH Bias
I
OZL
OFF-State Output
V
CC
=
5.5V, V
OUT
=
0.4V
-
20
A
Current, LOW Bias
I
CC
Supply Current
V
CC
=
5.5V, Inputs
=
GND
Enabled
7
10
mA
Inputs
=
4.5V, V
CC
=
5.5V
Disabled
9.4
14
5
www.fairchildsemi.com
DM74ALS251
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
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