1/11
August 2001
s
HIGH SPEED :
t
PD
= 11 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
= 6mA (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 257
DESCRIPTION
The M74HC257 is an high speed CMOS QUAD 2
CHANNEL MULTIPLEXER (3-STATE) fabricated
with silicon gate C
2
MOS technology.
This IC is composed of an independent 2-channel
multiplexer with common SELECT and ENABLE
(OE) input.
The M74HC257 is a non-inverting multiplexer.
When the ENABLE input is held "High", outputs of
the IC become in a High-Impedance state. If
SELECT input is held low, "A" data is selected,
when SELECT is high , "B" data is chosen.
All inputs are equipped with protection circuits
against static discharge and transient excess
voltage.
M74HC257
QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
PIN CONNECTION AND IEC LOGIC SYMBOLS
ORDER CODES
PACKAGE
TUBE
T & R
DIP
M74HC257B1R
SOP
M74HC257M1R
M74HC257RM13TR
TSSOP
M74HC257TTR
TSSOP
DIP
SOP
M74HC257
2/11
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
TRUTH TABLE
X : Don't Care
Z : High Impedance
LOGIC DIAGRAM
This logic diagram has not be used to estimate propagation delays
PIN No
SYMBOL
NAME AND FUNCTION
1
SELECT
Common Data Select
Input
2, 5, 14, 11
1A to 4A
Data Input From Source A
3, 6, 13, 10
1B to 4B
Data Input From Source B
4, 7, 12, 9
1Y to 4Y
3 State Multiplexer
Outputs
15
OE
3 State Output Enable
Inputs (Active Low)
8
GND
Ground (0V)
16
Vcc
Positive Supply Voltage
INPUTS
OUTPUT
OE
SELECT
A
B
Y
H
X
X
X
Z
L
L
L
X
L
L
L
H
X
H
L
H
X
L
L
L
H
X
H
H
M74HC257
3/11
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
RECOMMENDED OPERATING CONDITIONS
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
35
mA
I
CC
or I
GND
DC V
CC
or Ground Current
70
mA
P
D
Power Dissipation
500(*)
mW
T
stg
Storage Temperature
-65 to +150
C
T
L
Lead Temperature (10 sec)
300
C
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
M74HC257
4/11
DC SPECIFICATIONS
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
=-6.0 mA
4.18
4.31
4.13
4.10
6.0
I
O
=-7.8 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
=6.0 mA
0.17
0.26
0.33
0.40
6.0
I
O
=7.8 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
M74HC257
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
/4 (per
Channel)
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
50
25
60
75
90
ns
4.5
7
12
15
19
6.0
6
10
13
15
t
PLH
t
PHL
Propagation Delay
Time
(A, B - Y)
2.0
50
45
100
125
150
ns
4.5
13
20
25
30
6.0
11
17
21
26
2.0
150
62
140
175
210
ns
4.5
18
28
35
42
6.0
15
24
30
36
t
PLH
t
PHL
Propagation Delay
Time
(SELECT - Y)
2.0
50
45
100
125
150
ns
4.5
13
20
25
30
6.0
11
17
21
26
2.0
150
62
140
175
210
ns
4.5
18
28
35
42
6.0
15
24
30
36
t
PZL
t
PZH
High Impedance
Output Enable
Time
2.0
50
R
L
= 1 K
40
110
140
165
ns
4.5
12
22
28
33
6.0
10
19
24
28
2.0
150
R
L
= 1 K
57
150
190
225
ns
4.5
17
30
38
45
6.0
14
26
32
38
t
PLZ
t
PHZ
High Impedance
Output Disable
Time
2.0
50
R
L
= 1 K
28
140
175
210
ns
4.5
14
28
35
42
6.0
13
24
30
36
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
10
10
10
pF
C
OUT
Output
Capacitance
10
pF
C
PD
Power Dissipation
Capacitance (note
1)
47
pF
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