Page 1
TECHNICAL DATA
8-Input Data Selector/Multiplexer
with 3-State Outputs
High-Speed Silicon-Gate CMOS
The IN74AC251 is identical in pinout to the LS/ALS251,
HC/HCT251. The device inputs are compatible with standard CMOS
outputs; with pullup resistors, they are compatible with LS/ALS
outputs.
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 IN74AC251 to be used in busoriented systems.
•
Outputs Directly Interface to CMOS, NMOS, and TTL
•
Operating Voltage Range: 2.0 to 6.0 V
•
Low Input Current: 1.0 µA; 0.1 µA @ 25°C
•
High Noise Immunity Characteristic of CMOS Devices
•
Outputs Source/Sink 24 mA
IN74AC251
ORDERING INFORMATION
IN74AC251N Plastic
IN74AC251D SOIC
TA = -40° to 85° C for all
packages
PIN ASSIGNMENT
LOGIC DIAGRAM
PIN 16 =V
PIN 8 = GND
CC
FUNCTION TABLE
Inputs Outputs
A2 A1 A0 Output
Enable
XX X H Z Z
L L L L D0 D0
L L H L D1 D1
L H L L D2 D2
L H H L D3 D3
H L L L D4 D4
H L H L D5 D5
H H L L D6 D6
H H H L D7 D7
D0,D1...D7=the level of the respective D
input
Z = high-impedance st ate
X = don’t care
YY
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IN74AC251
MAXIMUM RATINGS
*
Symbol Parameter Value Unit
V
CC
V
V
OUT
I
IN
I
OUT
I
CC
P
DC Supply Voltage (Referenced to GND) -0.5 to +7.0 V
DC Input Voltage (Referenced to GND) -0.5 to VCC +0.5 V
IN
DC Output Voltage (Referenced to GND) -0.5 to VCC +0.5 V
DC Input Current, per Pin
DC Output Sink/Source Current, per Pin
DC Supply Current, VCC and GND Pins
Power Dissipation in Still Air, Plastic DIP+
D
SOIC Package+
±
20
±
50
±
50
750
500
Tstg Storage Temperature -65 to +150
T
Lead Temperature, 1 mm from Case for 10 Seconds
L
260
(Plastic DIP or SOIC Package)
*
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 125°C
SOIC Package: : - 7 mW/°C from 65° to 125°C
mA
mA
mA
mW
°
C
°
C
RECOMMENDED OPERATING CONDITIONS
Symbol Parameter Min Max Unit
V
CC
VIN, V
T
J
T
A
I
OH
I
OL
tr, t
f
*
VIN from 30% to 70% V
This device c ontains p rote ction ci rcuitr y to guard a gainst damage d ue to high st atic voltages or electr ic
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
GND≤(V
Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or V
Unused outputs must be left open.
DC Supply Voltage (Referenced to GND) 2.0 6.0 V
DC Input Voltage, Output Voltage (Referenced to GND) 0 V
OUT
Junction Temperature (PDIP) 140
Operating Temperature, All Package Types -40 +85
Output Current - High -24 mA
Output Current - Low 24 mA
Input Rise and Fall Time
(except Schmitt Inputs)
IN
or V
OUT
)≤VCC.
CC
*
V
V
V
=3.0 V
CC
=4.5 V
CC
=5.5 V
CC
and V
IN
0
0
0
should be constrained to the range
OUT
CC
150
40
25
V
°
C
°
C
ns/V
CC
).
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IN74AC251
DC ELECTRICAL CHARACTERISTICS
(Voltages Referenced to GND)
Symbol Parameter Test Conditions V
V
Minimum High-Level
IH
V
=0.1 V or VCC-0.1 V 3.0
OUT
Input Voltage
V
Maximum Low -
IL
V
=0.1 V or VCC-0.1 V 3.0
OUT
Level Input Voltage
V
OH
Minimum High-Level
I
OUT
≤ -50 µA
Output Voltage
*
VIN= VIH or V
IL
IOH=-12 mA
I
=-24 mA
OH
I
=-24 mA
OH
V
OL
Maximum Low-Level
I
OUT
≤ 50 µA
Output Voltage
*
VIN=VIH or V
IL
IOL=12 mA
I
=24 mA
OL
I
=24 mA
OL
I
IN
Maximum Input
VIN=VCC or GND 5.5
Leakage Current
I
I
OZ
OLD
Maximum ThreeState Leakage
Current
+Minimum Dynamic
VIN(OE)= VIH or V
V
V
V
or GND
IN =VCC
OUT =VCC
OLD
or GND
=1.65 V Max 5.5 75 mA
IL
Output Current
I
OHD
+Minimum Dynamic
V
=3.85 V Min 5.5 -75 mA
OHD
Output Current
I
CC
Maximum Quiescent
VIN=VCC or GND 5.5 8.0 80
Supply Current
(per Package)
*
All outputs loaded; thresholds on input associated with output under test.
+Maximum test duration 2.0 ms, one output loaded at a time.
Note: I
IN
and I
@ 3.0 V are guaranteed to be less than or equal to the respective limit @ 5.5 V V
CC
V
4.5
5.5
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
5.5
CC
Guaranteed Limits
25 °C-40
2.1
3.15
3.85
0.9
1.35
1.65
2.9
4.4
5.4
2.56
3.86
4.86
0.1
0.1
0.1
0.36
0.36
0.36
±
0.1
±
0.5
°
C to
85°C
2.1
3.15
3.85
0.9
1.35
1.65
2.9
4.4
5.4
2.46
3.76
4.76
0.1
0.1
0.1
0.44
0.44
0.44
±
1.0
±
5.0
CC
Unit
V
V
V
V
µ
A
µ
A
µ
A
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IN74AC251
AC ELECTRICAL CHARACTERISTICS
(CL=50pF, Input tr=tf=3.0 ns)
Symbol Parameter V
t
PLH
Propagation Delay, Input A to
Output Y or Y (Figure 3)
t
PHL
Propagation Delay, Input A to
Output Y or Y (Figure 3)
t
PLH
Propagation Delay, Input D to
Output Y or Y (Figures 1,2)
t
PHL
Propagation Delay, Input D to
Output Y or Y (Figures 1,2)
t
PZH
Propagation Delay, Output Enable to
Output Y or Y (Figure 4)
t
PZL
Propagation Delay, Output Enable to
Output Y or Y (Figure 4)
t
PHZ
Propagation Delay, Output Enable to
Output Y or Y (Figure 4)
t
PLZ
Propagation Delay, Output Enable to
Output Y or Y (Figure 4)
C
IN
Maximum Input Capacitance 5.0 4.5 4 .5 pF
V
CC
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
3.3
5.0
*
Guaranteed Limits
25 °C-40
Min Max Min Max
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
17.5
12.5
17.5
12.5
14.0
10.0
14.0
10.0
11.0
8.0
11.0
8.0
11.5
9.5
11.0
8.0
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
°
C to
85°C
19.0
13.5
19.0
13.5
15.5
11.0
15.5
11.0
12.0
9.0
12.0
9.0
13.0
10.0
12.0
8.5
Unit
ns
ns
ns
ns
ns
ns
ns
ns
C
PD
*
Voltage Range 3.3 V is 3.3 V ±0.3 V
Power Dissipation Capacitance 70 pF
Voltage Range 5.0 V is 5.0 V ±0.5 V
Figure 1. Switching Waveforms Figure 2. Switching Waveforms
Typical @25°C,VCC=5.0 V
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IN74AC251
Figure 3. Switching Waveforms Figure 4. Switching Waveforms
EXPANDED LOGIC DIAGRAM
340
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