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8-Input Data Selector/Multiplexer
with 3-State Outputs
High-Performance Silicon-Gate CMOS
The IN74HC251 is identical in pinout to the LS/ALS251. The
device inputs are compatible with standard CMOS outputs; with pullup
resistors, they are compatible with LS/ALSTTL 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 IN74HC251 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
•
High Noise Immunity Characteristic of CMOS Devices
TECHNICAL DATA
IN74HC251
ORDERING INFORMATION
IN74HC251N Plastic
IN74HC251D SOIC
TA = -55° to 125° C for all packages
PIN ASSIGNMENT
LOGIC DIAGRAM
PIN 16 =V
PIN 8 = GND
CC
FUNCTION TABLE
Inputs Outputs
A2 A1 A0 OE Y Y
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
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IN74HC251
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) -1.5 to VCC +1.5 V
IN
DC Output Voltage (Referenced to GND) -0.5 to VCC +0.5 V
DC Input Current, per Pin
DC Output Current, per Pin
DC Supply Current, VCC and GND Pins
Power Dissipation in Still Air, Plastic DIP+
D
SOIC Package+
±
25
±
50
±
75
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
A
tr, t
f
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
Operating Temperature, All Package Types -55 +125
Input Rise and Fall Time (Figure 1) VCC =2.0 V
IN
or V
OUT
)≤VCC.
V
V
and V
IN
=4.5 V
CC
=6.0 V
CC
should be constrained to the range
OUT
0
0
0
CC
1000
500
400
°
V
C
ns
CC
).
312
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IN74HC251
DC ELECTRICAL CHARACTERISTICS
(Voltages Referenced to GND)
Symbol Parameter Test Conditions V
V
V
V
OH
V
OL
I
IN
Minimum High-Level
IH
Input Voltage
Maximum Low -
IL
Level Input Voltage
Minimum High-Level
Output Voltage
Maximum Low-Level
Output Voltage
Maximum Input
V
=0.1 V or VCC-0.1 V
OUT
≤
I
20 µA
OUT
V
=0.1 V or VCC-0.1 V
OUT
≤
I
20 µA
OUT
VIN=VIH or V
≤
I
OUT
VIN=VIH or V
≤
I
OUT
≤
I
OUT
VIN=VIH or V
≤
I
OUT
VIN=VIH or V
≤
I
OUT
≤
I
OUT
IL
20 µA
IL
4.0 mA
5.2 mA
IL
20 µA
IL
4.0 mA
5.2 mA
VIN=VCC or GND 6.0
Leakage Current
I
OZ
I
CC
Maximum ThreeState Leakage
Current
Maximum Quiescent
Supply Current
Output in High-Impedance
State
V
= VIL or V
IN
V
OUT=VCC
IH
or GND
VIN=VCC or GND
=0µA
I
OUT
(per Package)
V
CC
Guaranteed Limit
25 °C
to
≤
85
°
C
≤
125
°
-55°C
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
4.5
6.0
2.0
4.5
6.0
4.5
6.0
6.0
1.5
3.15
4.2
0.3
0.9
1.2
1.9
4.4
5.9
3.98
5.48
0.1
0.1
0.1
0.26
0.26
±
0.1
±
0.5
1.5
3.15
4.2
0.3
0.9
1.2
1.9
4.4
5.9
3.84
5.34
0.1
0.1
0.1
0.33
0.33
±
1.0
±
5.0
1.5
3.15
4.2
0.3
0.9
1.2
1.9
4.4
5.9
3.7
5.2
0.1
0.1
0.1
0.4
0.4
±
1.0
±
6.0 8.0 80 160
C
10
Unit
V
V
V
V
µ
A
µ
A
µ
A
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IN74HC251
AC ELECTRICAL CHARACTERISTICS
(CL=50pF,Input tr=tf=6.0 ns)
Symbol Parameter V
t
PLH
, t
Maximum Propagation Delay, Input D to
PHL
Output Y or Y (Figures 1,2 and 5)
t
PLH
, t
Maximum Propagation Delay , Input A to
PHL
Output Y or Y (Figures 3 and 5)
t
PLZ
, t
Maximum Propagation Delay , Output Enable to
PHZ
Output Y (Figures 4 and 6)
t
PZL
, t
Maximum Propagation Delay , Output Enable to
PZH
Output Y (Figures 4 and 6)
t
PLZ
, t
Maximum Propagation Delay , Output Enable to
PHZ
Output Y (Figures 4 and 6)
t
PZL
, t
Maximum Propagation Delay , Output Enable to
PZH
Output Y (Figures 4 and 6)
t
TLH
, t
Maximum Output Transition Time, Any Output
THL
(Figures 1 and 6)
C
IN
C
OUT
Maximum Input Capacitance - 10 10 10 pF
Maximum Three-State Output Capacitance
(Output in High-Impedance State)
V
CC
Guaranteed Limit
25 °C
≤85°C≤
125°C
Unit
to
-55°C
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
185
37
31
205
41
35
195
39
33
145
29
25
220
44
37
150
30
26
75
15
13
230
46
39
255
51
43
245
48
42
180
36
31
275
55
47
190
38
33
95
19
16
280
56
48
310
62
53
295
59
50
220
44
38
330
66
56
225
45
38
110
22
19
ns
ns
ns
ns
ns
ns
ns
-151515pF
314
Power Dissipation Capacitance (Per Package)
C
PD
Used to determine the no-load dynamic power
consumption: P
D=CPDVCC
2
f+ICCV
CC
Typical @25°C,V
36 pF
Figure 1. Switching Waveforms Figure 2. Switching Waveforms
=5.0 V
CC
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IN74HC251
Figure 3. Switching Waveforms Figure 4. Switching Waveforms
Figure 5. Test Circuit Figure 6.Test Circuit
EXPANDED LOGIC DIAGRAM
315
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