2000 Fairchild Semiconductor Corporation
DS012466
www.fairchildsemi.com
May 1995
Revised September 2000
7
4
LCX257
Low V
o
lt
age
Quad 2-
Input
Mul
t
i
p
lex
e
r w
i
th 5V T
o
l
e
ra
nt Input
s and
Out
puts
74LCX257
Low Voltage Quad 2-Input Multiplexer
with 5V Tolerant Inputs and Outputs
General Description
The LCX257 is a quad 2-input multiplexer with 3-STATE
outputs. Four bits of data from two sources can be selected
using a Common Data Select input. The four outputs
present the selected data in true (non inverted) form. The
outputs may be switched to a high impedance state by
placing a logic HIGH on the common Output Enable (OE)
input, allowing the outputs to interface directly with bus-ori-
ented systems.
The 74LCX257 is fabricated with advanced CMOS technol-
ogy to achieve high speed operation while maintaining
CMOS low power dissipation.
Features
s
5V tolerant inputs and outputs
s
2.3V3.6V V
CC
specifications provided
s
6.0 ns t
PD
max (V
CC
=
3.3V, I
n
Z
n
), 10
A I
CC
max
s
Power down high impedance inputs and outputs
s
Supports live insertion/withdrawal (Note 1)
s
Implements patented noise/EMI reduction circuitry
s
Latch-up performance exceeds 500 mA
s
ESD performance:
Human body model
>
2000V
Machine model
>
200V
Note 1: To ensure the high-impedance state during power up or down, OE
should be tied to V
CC
through a pull-up resistor: the minimum value or the
resistor is determined by the current-sourcing capability of the driver.
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Logic Symbols
IEEE/IEC
Connection Diagram
Pin Descriptions
Order Number
Package Number
Package Description
74LCX257M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
74LCX257SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74LCX257MTC
MTC16
16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
Pin Names
Description
S
Common Data Select Input
OE
3-STATE Output Enable Input
I
0a
I
0d
Data Inputs from Source 0
I
1a
I
1d
Data Inputs from Source 1
Z
a
Z
d
3-STATE Multiplexer Outputs
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2
74LCX257
Functional Description
The LCX257 is a quad 2-input multiplexer with 3-STATE
outputs. It selects four bits of data from two sources under
control of a Common Data Select input. When the Select
input is LOW, the I
0x
inputs are selected and when Select
is HIGH, the I
1x
inputs are selected. The data on the
selected inputs appears at the outputs in true (non
inverted) form. The device is the logic implementation of a
4-pole, 2-position switch where the position of the switch is
determined by the logic levels supplied to the Select input.
The logic equations for the outputs are shown below:
Z
a
=
OE (1
1a
S
+
I
0a
S)
Z
b
=
OE (1
1b
S
+
I
0b
S)
Z
c
=
OE (1
1c
S
+
I
0c
S)
Z
d
=
OE (1
1d
S
+
I
0d
S)
When the Output Enable (OE) is HIGH, the outputs are
forced to a high impedance state. If the outputs are tied
together, all but one device must be in the high impedance
state to avoid high currents that would exceed the maxi-
mum ratings. Designers should ensure the Output Enable
signals to 3-STATE devices whose outputs are tied
together are designed so there is no overlap.
Truth Table
H
=
HIGH Voltage Level
L
=
LOW Voltage Level
X
=
Immaterial
Z
=
High Impedance
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
Output
Select
Data
Outputs
Enable
Input
Inputs
OE
S
I
0
I
1
Z
H
X
X
X
Z
L
H
X
L
L
L
H
X
H
H
L
L
L
X
L
L
L
H
X
H
3
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7
4
LCX257
Absolute Maximum Ratings
(Note 1)
Recommended Operating Conditions
(Note 4)
Note 2: The Absolute Maximum Ratings are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated
at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the Absolute Maximum Ratings. The "Recom-
mended Operating Conditions" table will define the conditions for actual device operation.
Note 3: I
O
Absolute Maximum rating must be observed.
Note 4: Unused Inputs must be held HIGH or LOW. They may not float.
DC Electrical Characteristics
Symbol
Parameter
Value
Conditions
Units
V
CC
Supply Voltage
-
0.5 to
+
7.0
V
V
I
DC Input Voltage
-
0.5 to
+
7.0
V
V
O
DC Output Voltage
-
0.5 to
+
7.0
Output in 3-STATE
V
-
0.5 to V
CC
+
0.5
Output in HIGH or LOW State (Note 2)
I
IK
DC Input Diode Current
-
50
V
I
<
GND
mA
I
OK
DC Output Diode Current
-
50
V
O
<
GND
mA
+
50
V
O
>
V
CC
I
O
DC Output Source/Sink Current
50
mA
I
CC
DC Supply Current per Supply Pin
100
mA
I
GND
DC Ground Current per Ground Pin
100
mA
T
STG
Storage Temperature
-
65 to
+
150
C
Symbol
Parameter
Min
Max
Units
V
CC
Supply Voltage
Operating
2.0
3.6
V
Data Retention
1.5
3.6
V
I
Input Voltage
0
5.5
V
V
O
Output Voltage
HIGH or LOW State
0
V
CC
V
3-STATE
0
5.5
I
OH
/I
OL
Output Current
V
CC
=
3.0V
-
3.6V
24
V
CC
=
2.7V
-
3.0V
12
mA
V
CC
=
2.3V
-
2.7V
8
T
A
Free-Air Operating Temperature
-
40
85
C
t/
V
Input Edge Rate, V
IN
=
0.8V2.0V, V
CC
=
3.0V
0
10
ns/V
Symbol
Parameter
Conditions
V
CC
T
A
=
-
40
C to
+
85
C
Units
(V)
Min
Max
V
IH
HIGH Level Input Voltage
2.3
-
2.7
1.7
V
2.7
-
3.6
2.0
V
IL
LOW Level Input Voltage
2.3
-
2.7
0.7
V
2.7
-
3.6
0.8
V
OH
HIGH Level Output Voltage
I
OH
=
-
100
A
2.3
-
3.6
V
CC
-
0.2
V
I
OH
=
-
8 mA
2.3
1.8
I
OH
=
-
12 mA
2.7
2.2
I
OH
=
-
18 mA
3.0
2.4
I
OH
=
-
24 mA
3.0
2.2
V
OL
LOW Level Output Voltage
I
OL
=
100
A
2.3
-
3.6
0.2
V
I
OL
=
8 mA
2.3
0.6
I
OL
=
12 mA
2.7
0.4
I
OL
=
16 mA
3.0
0.4
I
OL
=
24 mA
3.0
0.55
I
I
Input Leakage Current
0
V
I
5.5V
2.3
-
3.6
5.0
A
I
OZ
3-STATE Output Leakage
0
V
O
5.5V
2.3
-
3.6
5.0
A
V
I
=
V
IH
or V
IL
I
OFF
Power-Off Leakage Current
V
I
or V
O
=
5.5V
0
10
A
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4
74LCX257
DC Electrical Characteristics
(Continued)
Note 5: Outputs disabled or 3-STATE only.
AC Electrical Characteristics
Note 6: Skew is defined as the absolute value of the difference between the actual propagation delay for any two separate outputs of the same device. The
specification applies to any outputs switching in the same direction, either HIGH-to-LOW (t
OSHL
) or LOW-to-HIGH (t
OSLH
).
Dynamic Switching Characteristics
Capacitance
Symbol
Parameter
Conditions
V
CC
T
A
=
-
40
C to
+
85
C
Units
(V)
Min
Max
I
CC
Quiescent Supply Current
V
I
=
V
CC
or GND
2.3
-
3.6
10
A
3.6V
V
I
, V
O
5.5V (Note 5)
2.3
-
3.6
10
I
CC
Increase in I
CC
per Input
V
IH
=
V
CC
-
0.6V
2.3
-
3.6
500
A
Symbol
Parameter
T
A
=
-
40
C to
+
85
C, R
L
=
500
Units
V
CC
=
3.3V
0.3V
V
CC
=
2.7V
V
CC
=
2.5V
0.2V
C
L
=
50 pF
C
L
=
50 pF
C
L
=
30 pF
Min
Max
Min
Max
Min
Max
t
PHL
Propagation Delay
1.5
7.0
1.5
8.5
1.5
9.1
ns
t
PLH
S
Z
n
1.5
7.0
1.5
8.5
1.5
9.1
t
PHL
Propagation Delay
1.5
6.0
1.5
6.5
1.5
7.2
ns
t
PLH
I
n
Z
n
1.5
6.0
1.5
6.5
1.5
7.2
t
PZL
Output Enable Time
1.5
7.0
1.5
8.5
1.5
9.1
ns
t
PZH
OE
Z
n
1.5
7.0
1.5
8.5
1.5
9.1
t
PLZ
Output Disable Time
1.5
5.5
1.5
6.0
1.5
6.6
ns
t
PHZ
OE
Z
n
1.5
5.5
1.5
6.0
1.5
6.6
t
OSHL
Output to Output Skew (Note 6)
1.0
ns
t
OSLH
1.0
Symbol
Parameter
Conditions
V
CC
T
A
=
25
C
Units
(V)
Typical
V
OLP
Quiet Output Dynamic Peak V
OL
C
L
=
50 pF, V
IH
=
3.3V, V
IL
=
0V
3.3
0.8
V
C
L
=
30 pF, V
IH
=
2.5V, V
IL
=
0V
2.5
0.6
V
OLV
Quiet Output Dynamic Valley V
OL
C
L
=
50 pF, V
IH
=
3.3V, V
IL
=
0V
3.3
-
0.8
V
C
L
=
30 pF, V
IH
=
2.5V, V
IL
=
0V
2.5
-
0.6
Symbol
Parameter
Conditions
Typical
Units
C
IN
Input Capacitance
V
CC
=
Open, V
I
=
0V or V
CC
7
pF
C
OUT
Output Capacitance
V
CC
=
3.3V, V
I
=
0V or V
CC
8
pF
C
PD
Power Dissipation Capacitance
V
CC
=
3.3V, V
I
=
0V or V
CC
, f
=
10 MHz
25
pF
5
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7
4
LCX257
AC LOADING and WAVEFORMS
Generic for LCX Family
FIGURE 1. AC Test Circuit (C
L
includes probe and jig capacitance)
Waveform for Inverting and Non-Inverting Functions
Propagation Delay. Pulse Width and t
rec
Waveforms
3-STATE Output Low Enable and
Disable Times for Logic
3-STATE Output High Enable and
Disable Times for Logic
Setup Time, Hold Time and Recovery Time for Logic
t
rise
and t
fall
FIGURE 2. Waveforms
(Input Characteristics; f =1MHz, t
R
= t
F
= 3ns)
Test
Switch
t
PLH
, t
PHL
Open
t
PZL
, t
PLZ
6V at V
CC
=
3.3
0.3V
V
CC
x 2 at V
CC
=
2.5
0.2V
t
PZH
,t
PHZ
GND
Symbol
V
CC
3.3V
0.3V
2.7V
2.5V
0.2V
V
mi
1.5V
1.5V
V
CC
/2
V
mo
1.5V
1.5V
V
CC
/2
V
x
V
OL
+
0.3V
V
OL
+
0.3V
V
OL
+
0.15V
V
y
V
OH
-
0.3V
V
OH
-
0.3V
V
OH
-
0.15V
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