IN74ACT251
1
8-I
NPUT
D
ATA
S
ELECTOR
/M
ULTIPLEXER
WITH
3-S
TATE
O
UTPUTS
High-Speed Silicon-Gate CMOS
The IN74ACT251 is identical in pinout to the LS/ALS251,
HC/HCT251. The IN74ACT251 may be used as a level converter
for interfacing TTL or NMOS outputs to High Speed CMOS inputs.
The device selects one of the eight binary Data Inputs, as
determined by the Address Inputs. The Output Enable pin must be
at a low level for the selected data to appear at the outputs. If
Output Enable is high, the Y and the Y outputs are in the high-
impedance state. This 3-State feature allows the IN74ACT251 to
be used in bus-oriented systems.
TTL/NMOS Compatible Input Levels
Outputs Directly Interface to CMOS, NMOS, and TTL
Operating Voltage Range: 4.5 to 5.5 V
Low Input Current: 1.0 A; 0.1 A @ 25C
Outputs Source/Sink 24 mA
ORDERING INFORMATION
IN74ACT251N Plastic
IN74ACT251D SOIC
T
A
= -40
to 85 C for all
packages
PIN ASSIGNMENT
FUNCTION TABLE
Inputs Outputs
A2 A1
A0 Output
Enable
Y
Y
X X X
H
Z Z
L L L
L D0
0
D
L L H
L D1
1
D
L H L
L D2
2
D
L H H
L D3
3
D
H L L
L D4
4
D
H L H
L D5
5
D
H H L
L D6
6
D
H H H
L D7
7
D
D0,D1...D7=the level of the
respective D input
Z = high-impedance state
X = don't care
LOGIC DIAGRAM
PIN 16 =V
CC
PIN 8 = GND
IN74ACT251
2
MAXIMUM RATINGS
*
Symbol Parameter
Value
Unit
V
CC
DC Supply Voltage (Referenced to GND)
-0.5 to +7.0
V
V
IN
DC Input Voltage (Referenced to GND)
-0.5 to V
CC
+0.5
V
V
OUT
DC Output Voltage (Referenced to GND)
-0.5 to V
CC
+0.5
V
I
IN
DC Input Current, per Pin
20
mA
I
OUT
DC Output Sink/Source Current, per Pin
50
mA
I
CC
DC Supply Current, V
CC
and GND Pins
50
mA
P
D
Power Dissipation in Still Air, Plastic DIP+
SOIC Package+
750
500
mW
Tstg
Storage Temperature
-65 to +150
C
T
L
Lead Temperature, 1 mm from Case for 10
Seconds
(Plastic DIP or SOIC Package)
260
C
*
Maximum Ratings are those values beyond which damage to the device may occur.
Functional operation should be restricted to the Recommended Operating Conditions.
+Derating - Plastic DIP: - 10 mW/
C from 65 to 125C
SOIC Package: : - 7 mW/
C from 65 to 125C
RECOMMENDED OPERATING CONDITIONS
Symbol Parameter Min
Max
Unit
V
CC
DC Supply Voltage (Referenced to GND)
4.5
5.5
V
V
IN
, V
OUT
DC Input Voltage, Output Voltage (Referenced to
GND)
0 V
CC
V
T
J
Junction Temperature (PDIP)
140
C
T
A
Operating Temperature, All Package Types
-40
+85
C
I
OH
Output Current - High
-24
mA
I
OL
Output Current - Low
24
mA
t
r
, t
f
Input Rise and Fall Time
*
(except Schmitt Inputs)
V
CC
=4.5 V
V
CC
=5.5 V
0
0
10
8.0
ns/V
*
V
IN
from 0.8 V to 2.0 V
This device contains protection circuitry to guard against damage due to high static
voltages or electric fields. However, precautions must be taken to avoid applications of any voltage
higher than maximum rated voltages to this high-impedance circuit. For proper operation, V
IN
and
V
OUT
should be constrained to the range GND
(V
IN
or V
OUT
)
V
CC
.
Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or
V
CC
). Unused outputs must be left open.
IN74ACT251
3
DC ELECTRICAL CHARACTERISTICS(Voltages Referenced to GND)
V
CC
Guaranteed
Limits
Symbol Parameter
Test
Conditions
V 25
C -40C to
85
C
Unit
V
IH
Minimum
High-
Level Input
Voltage
V
OUT
=0.1 V or V
CC
-0.1 V
4.5
5.5
2.0
2.0
2.0
2.0
V
V
IL
Maximum Low -
Level Input
Voltage
V
OUT
=0.1 V or V
CC
-0.1 V
4.5
5.5
0.8
0.8
0.8
0.8
V
V
OH
Minimum
High-
Level Output
Voltage
I
OUT
-50 A
4.5
5.5
4.4
5.4
4.4
5.4
V
*
V
IN
=V
IH
or V
IL
I
OH
=-24 mA
I
OH
=-24 mA
4.5
5.5
3.86
4.86
3.76
4.76
V
OL
Maximum
Low-
Level Output
Voltage
I
OUT
50 A
4.5
5.5
0.1
0.1
0.1
0.1
V
*
V
IN
=V
IH
or V
IL
I
OL
=24 mA
I
OL
=24 mA
4.5
5.5
0.36
0.36
0.44
0.44
I
IN
Maximum
Input
Leakage Current
V
IN
=V
CC
or GND
5.5
0.1
1.0
A
I
CCT
Additional Max.
I
CC
/Input
V
IN
=V
CC
- 2.1 V
5.5
1.5
mA
I
OZ
Maximum
Three-
State Leakage
Current
V
IN
(OE)= V
IH
or V
IL
V
IN
=V
CC
or GND
V
OUT
=V
CC
or GND
5.5
0.5
5.0
A
I
OLD
+Minimum
Dynamic Output
Current
V
OLD
=1.65 V Max
5.5
75
mA
I
OHD
+Minimum
Dynamic Output
Current
V
OHD
=3.85 V Min
5.5
-75
mA
I
CC
Maximum
Quiescent Supply
Current
(per Package)
V
IN
=V
CC
or GND
5.5
8.0
80
A
*
All outputs loaded; thresholds on input associated with output under test.
+Maximum test duration 2.0 ms, one output loaded at a time.
IN74ACT251
4
AC ELECTRICAL CHARACTERISTICS(V
CC
=5.0 V
10%, C
L
=50pF, Input t
r
=t
f
=3.0 ns)
Guaranteed
Limits
Symbol Parameter 25
C -40C to
85
C
Unit
Min
Max
Min
Max
t
PLH
Propagation Delay, Input A to
Output Y or
Y
(Figure 3)
2.5 15.5
2.0 17.0
ns
t
PHL
Propagation Delay, Input A to
Output Y or
Y
(Figure 3)
2.5 16.5
2.5 18.5
ns
t
PLH
Propagation Delay, Input D to
Output Y or
Y
(Figures 1,2)
2.5 12.0
2.0 13.0
ns
t
PHL
Propagation Delay, Input D to
Output Y or
Y
(Figures 1,2)
2.5 12.5
2.5 14.0
ns
t
PZH
Propagation Delay, Output Enable to
Output Y or
Y
(Figure 4)
1.5 8.5 1.5 9.0
ns
t
PZL
Propagation Delay, Output Enable to
Output Y or
Y
(Figure 4)
1.5 8.5 1.5 9.5
ns
t
PHZ
Propagation Delay, Output Enable to
Output Y or
Y
(Figure 4)
2.0 12.0
2.0 13.0
ns
t
PLZ
Propagation Delay, Output Enable to
Output Y or
Y
(Figure 4)
1.5 8.5 1.5 9.0
ns
C
IN
Maximum Input Capacitance
4.5
4.5
pF
Typical @25
C,V
CC
=5.0
V
C
PD
Power Dissipation Capacitance
70
pF
Figure 1. Switching Waveforms
Figure 2. Switching Waveforms
IN74ACT251
5
Figure 3. Switching Waveforms
Figure 4. Switching Waveforms
EXPANDED LOGIC DIAGRAM
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