1/11
July 2001
s
HIGH SPEED :
t
PD
= 17 ns (TYP.) at V
CC
= 6V
s
LOW POWER DISSIPATION:
I
CC
=4
A(MAX.) at T
A
=25C
s
HIGH NOISE IMMUNITY:
V
NIH
= V
NIL
= 28 % V
CC
(MIN.)
s
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 4mA (MIN)
s
BALANCED PROPAGATION DELAYS:
t
PLH
t
PHL
s
WIDE OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 2V to 6V
s
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 251
DESCRIPTION
The M74HC251 is an high speed CMOS
8-CHANNEL MULTIPLEXER (3-STATE)
fabricated with silicon gate C
2
MOS technology.
This Multiplexer features both true (Y) and
complement (W) outputs as well as STROBE
input. When the STROBE is high, both outputs are
in the high impedance state. When enabled,
address information on the data select inputs
determines which data input is routed to Y and W.
All inputs are equipped with protection circuits
against static discharge and transient excess
voltage.
M74HC251
8-CHANNEL MULTIPLEXER (3-STATE)
PIN CONNECTION AND IEC LOGIC SYMBOLS
ORDER CODES
PACKAGE
TUBE
T & R
DIP
M74HC251B1R
SOP
M74HC251M1R
M74HC251RM13TR
TSSOP
M74HC251TTR
TSSOP
DIP
SOP
M74HC251
2/11
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
TRUTH TABLE
X : Don't Care
Z : High Impedance
PIN No
SYMBOL
NAME AND FUNCTION
4, 3, 2, 1, 15,
14, 13, 12
D0 to D7
Multiplexer Inputs
5
Y
Multiplexer Output
6
W
Complementary Multi-
plexer Output
7
STROBE
3 State Output Enable
Input
11, 10, 9
A, B, C
Select Inputs
8
GND
Ground (0V)
16
Vcc
Positive Supply Voltage
INPUTS
OUTPUTS
STROBE
Y
W
C
B
A
S
X
X
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
M74HC251
3/11
LOGIC DIAGRAM
This logic diagram has not be used to estimate propagation delays
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied
(*) 500mW at 65
C; derate to 300mW by 10mW/
C from 65
C to 85
C
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
-0.5 to +7
V
V
I
DC Input Voltage
-0.5 to V
CC
+ 0.5
V
V
O
DC Output Voltage
-0.5 to V
CC
+ 0.5
V
I
IK
DC Input Diode Current
20
mA
I
OK
DC Output Diode Current
20
mA
I
O
DC Output Current
25
mA
I
CC
or I
GND
DC V
CC
or Ground Current
50
mA
P
D
Power Dissipation
500(*)
mW
T
stg
Storage Temperature
-65 to +150
C
T
L
Lead Temperature (10 sec)
300
C
M74HC251
4/11
RECOMMENDED OPERATING CONDITIONS
DC SPECIFICATIONS
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
2 to 6
V
V
I
Input Voltage
0 to V
CC
V
V
O
Output Voltage
0 to V
CC
V
T
op
Operating Temperature
-55 to 125
C
t
r
, t
f
Input Rise and Fall Time
V
CC
= 2.0V
0 to 1000
ns
V
CC
= 4.5V
0 to 500
ns
V
CC
= 6.0V
0 to 400
ns
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
V
IH
High Level Input
Voltage
2.0
1.5
1.5
1.5
V
4.5
3.15
3.15
3.15
6.0
4.2
4.2
4.2
V
IL
Low Level Input
Voltage
2.0
0.5
0.5
0.5
V
4.5
1.35
1.35
1.35
6.0
1.8
1.8
1.8
V
OH
High Level Output
Voltage
2.0
I
O
=-20
A
1.9
2.0
1.9
1.9
V
4.5
I
O
=-20
A
4.4
4.5
4.4
4.4
6.0
I
O
=-20
A
5.9
6.0
5.9
5.9
4.5
I
O
=-4.0 mA
4.18
4.31
4.13
4.10
6.0
I
O
=-5.2 mA
5.68
5.8
5.63
5.60
V
OL
Low Level Output
Voltage
2.0
I
O
=20
A
0.0
0.1
0.1
0.1
V
4.5
I
O
=20
A
0.0
0.1
0.1
0.1
6.0
I
O
=20
A
0.0
0.1
0.1
0.1
4.5
I
O
=4.0 mA
0.17
0.26
0.33
0.40
6.0
I
O
=5.2 mA
0.18
0.26
0.33
0.40
I
I
Input Leakage
Current
6.0
V
I
= V
CC
or GND
0.1
1
1
A
I
OZ
High Impedance
Output Leakage
Current
6.0
V
I
= V
IH
or V
IL
V
O
= V
CC
or GND
0.5
5
10
A
I
CC
Quiescent Supply
Current
6.0
V
I
= V
CC
or GND
4
40
80
A
M74HC251
5/11
AC ELECTRICAL CHARACTERISTICS (C
L
= 50 pF, Input t
r
= t
f
= 6ns)
CAPACITIVE CHARACTERISTICS
1) C
PD
is defined as the value of the IC's internal equivalent capacitance which is calculated from the operating current consumption without
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
CC(opr)
= C
PD
x V
CC
x f
IN
+ I
CC
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
t
TLH
t
THL
Output Transition
Time
2.0
30
75
95
115
ns
4.5
8
15
19
23
6.0
7
13
16
20
t
PLH
t
PHL
Propagation Delay
Time
(D - Y, W)
2.0
64
130
165
195
ns
4.5
16
26
33
39
6.0
14
22
28
33
t
PHL
Propagation Delay
Time
(A, B, C -Y, W)
2.0
80
160
200
240
ns
4.5
20
32
40
48
6.0
17
27
34
41
t
PZL
t
PZH
High Impedance
Output Enable
Time
2.0
R
L
= 1 K
36
90
115
135
ns
4.5
11
18
23
27
6.0
9
15
20
23
t
PLZ
t
PHZ
High Impedance
Output Disable
Time
2.0
R
L
= 1 K
26
85
105
130
ns
4.5
13
17
21
26
6.0
11
14
18
22
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
C
IN
Input Capacitance
5.0
5
10
10
10
pF
C
PD
Power Dissipation
Capacitance (note
1)
5.0
62
pF
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