DM74ALS251 3-STATE 1-of-8 Line Data Selector/Multiplexer
April 1984
Revised April 2000
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:
Order Number
DM74ALS251M
DM74ALS251SJ
DM74ALS251N
Package Number
M16A
M16D
N16E
Package Description
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
Function Table
Inputs
Select
C
X
L
L
L
L
H
H
H
H
B
X
L
L
H
H
L
L
H
H
A
X
L
H
L
H
L
H
L
H
Strobe
S
H
L
L
L
L
L
L
L
L
Y
Z
D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
W
Z
D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
Outputs
H
=
HIGH Level
L
=
LOW Level
X
=
Don't Care
Z
=
High Impedance (OFF)
D0 thru D7
=
The Level of the Respective D Input
© 2000 Fairchild Semiconductor Corporation
DS006214
www.fairchildsemi.com
DM74ALS251
Absolute Maximum Ratings
(Note 1)
Supply Voltage, V
CC
Input Voltage
Voltage Applied to Disabled Output
Operating Free Air Temperature Range
Storage Temperature Range
Typical
θ
JA
N Package
M Package
78.0°C/W
107.0°C/W
7V
7V
5.5V
0°C to
+70°C
−65°C
to
+150°C
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
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
0
Parameter
Min
4.5
2
0.8
−2.6
24
70
Nom
5
Max
5.5
Units
V
V
V
mA
mA
°C
Electrical Characteristics
over recommended operating free air temperature range. All typical values are measured at V
CC
=
5V, T
A
=
25°C.
Symbol
V
IK
V
OH
V
OL
I
I
I
IH
I
IL
I
O
I
OZH
I
OZL
I
CC
HIGH Level
Output Voltage
LOW Level
Output Voltage
Input Current at Maximum
Input Voltage
HIGH Level Input Current
LOW Level Input Current
Output Drive Current
OFF-State Output
Current, HIGH Bias
OFF-State Output
Current, LOW Bias
Supply Current
Parameter
Input Clamp Voltage
Conditions
V
CC
=
4.5V, I
IN
= −18
mA
V
CC
=
4.5V, I
OH
=
Max
I
OH
= −400 µA,
V
CC
=
4.5V to 5.5V
V
CC
=
4.5V
V
CC
=
5.5V, V
IH
=
7V
V
CC
=
5.5V, V
IH
=
2.7V
V
CC
=
5.5V, V
IN
=
0.4V
V
CC
=
5.5V, V
OUT
=
2.25V
V
CC
=
5.5V, V
OUT
=
2.7V
V
CC
=
5.5V, V
OUT
=
0.4V
V
CC
=
5.5V, Inputs
=
GND
Inputs
=
4.5V, V
CC
=
5.5V
Enabled
Disabled
7
9.4
−30
I
OL
=
24 mA
2.4
V
CC
−2
0.35
0.5
0.1
20
−0.1
−112
20
−20
10
14
3.2
Min
Typ
Max
−1.5
Units
V
V
V
V
mA
µA
mA
mA
µA
µA
mA
3
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