The LCX157 is a quad 2-input multiplexer. It selects four
bits of data from two sources under the control of a com-
mon Select input (S). The Enable input (E) is active-LOW.
When E is HIGH, all of the outputs (Z) are forced LOW
regardless of all other inputs. The LCX157 is the logic
implementation of a 4-pole, 2-position switch where the
position of the switch is determined by the logic levels sup-
plied to the Select input. The logic equations for the outputs
are shown below:
Z
a
=
E • (I
1a
• S
+
I
0a
• S)
Z
b
=
E • (I
1b
• S
+
I
0b
• S)
Z
c
=
E • (I
1c
• S
+
I
0c
• S)
Z
d
=
E • (I
1d
• S
+
I
0d
• S)
A common use of the LCX157 is the moving of data from
two groups of registers to four common output busses. The
particular register from which the data comes is determined
by the state of the Select input. A less obvious use is as a
function generator. The LCX157 can generate any four of
the sixteen different functions of two variables with one
variable common. This is useful for implementing gating
functions.
Truth Table
Inputs
E
H
L
L
L
L
S
X
H
H
L
L
I
0
X
X
X
L
H
I
1
X
L
H
X
X
Outputs
Z
L
L
H
L
H
H
=
HIGH Voltage Level
L
=
LOW Voltage Level
X
=
Immaterial
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.
www.fairchildsemi.com
2
74LCX157
Absolute Maximum Ratings
(Note 1)
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
I
CC
I
GND
T
STG
Parameter
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Source/Sink Current
DC Supply Current per Supply Pin
DC Ground Current per Ground Pin
Storage Temperature
Value
Conditions
Units
V
V
Output in HIGH or LOW State (Note 2)
V
I
<
GND
V
O
<
GND
V
O
>
V
CC
V
mA
mA
mA
mA
mA
−
0.5 to
+
7.0
−
0.5 to
+
7.0
−
0.5 to V
CC
+
0.5
−
50
−
50
+
50
±
50
±
100
±
100
−
65 to
+
150
°
C
Recommended Operating Conditions
(Note 3)
Symbol
V
CC
V
I
V
O
I
OH
/I
OL
Supply Voltage
Input Voltage
Output Voltage
Output Current
HIGH or LOW State
V
CC
=
3.0V
−
3.6V
V
CC
=
2.7V
−
3.0V
V
CC
=
2.3V
−
2.7V
T
A
Free-Air Operating Temperature
Input Edge Rate, V
IN
=
0.8V
−
2.0V, V
CC
=
3.0V
Parameter
Operating
Data Retention
Min
2.0
1.5
0
0
Max
3.6
3.6
5.5
V
CC
Units
V
V
V
mA
±
24
±
12
±
8
−
40
0
85
10
°
C
ns/V
∆
t/
∆
V
Note 1:
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 2:
I
O
Absolute Maximum Rating must be observed.
Note 3:
Unused inputs must be held HIGH or LOW. They may not float.
DC Electrical Characteristics
Symbol
V
IH
V
IL
V
OH
Parameter
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Voltage
I
OH
= −100 µA
I
OH
= −8
mA
I
OH
= −12
mA
I
OH
= −18
mA
I
OH
= −24
mA
V
OL
LOW Level Output Voltage
I
OL
=
100
µA
I
OH
=
8 mA
I
OL
=
12 mA
I
OL
=
16 mA
I
OL
=
24 mA
I
I
I
OFF
I
CC
∆I
CC
Input Leakage Current
Power-Off Leakage Current
Quiescent Supply Current
Increase in I
CC
per Input
0
≤
V
I
≤
5.5V
V
I
or V
O
=
5.5V
V
I
=
V
CC
or GND
3.6V
≤
V
I
≤
5.5V
V
IH
=
V
CC
−0.6V
Conditions
V
CC
(V)
2.3
−
2.7
2.7
−
3.6
2.3
−
2.7
2.7
−
3.6
2.3
−
3.6
2.3
2.7
3.0
3.0
2.3
−
3.6
2.3
2.7
3.0
3.0
2.3
−
3.6
0
2.3
−
3.6
2.3
−
3.6
2.3
−
3.6
V
CC
−
0.2
1.8
2.2
2.4
2.2
0.2
0.6
0.4
0.4
0.55
±5.0
10
10
±10
500
µA
µA
µA
µA
V
V
T
A
= −40°C
to
+85°C
Min
1.7
2.0
0.7
0.8
Max
V
V
Units
3
www.fairchildsemi.com
74LCX157
AC Electrical Characteristics
T
A
= −40°C
to
+85°C,
R
L
=
500Ω
Symbol
Parameter
V
CC
=
3.3V
±
0.3V
C
L
=
50 pF
Min
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
OSHL
t
OSLH
Propagation Delay
S→Z
n
Propagation Delay
E→Z
n
Propagation Delay
I
n
→Z
n
Output to Output Skew
(Note 4)
1.5
1.5
1.5
1.5
1.5
1.5
Max
7.0
7.0
7.0
7.0
5.8
5.8
1.0
1.0
V
CC
=
2.7V
C
L
=
50 pF
Min
1.5
1.5
1.5
1.5
1.5
1.5
Max
8.0
8.0
8.0
8.0
6.3
6.3
V
CC
=
2.5V
±
0.2V
C
L
=
30 pF
Min
1.5
1.5
1.5
1.5
1.5
1.5
Max
8.4
8.4
8.4
8.4
7.0
7.0
ns
ns
ns
ns
Units
Note 4:
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
). Parameter guaranteed by design.
Dynamic Switching Characteristics
Symbol
V
OLP
V
OLV
Parameter
Quiet Output Dynamic Peak V
OL
Quiet Output Dynamic Valley V
OL
Conditions
C
L
=
50 pF, V
IH
=
3.3V, V
IL
=
0V
CL= 30 pF, V
IH
= 2.5V, V
IL
= 0V
C
L
=
50 pF, V
IH
=
3.3V, V
IL
=
0V
CL= 30 pF, V
IH
= 2.5V, V
IL
= 0V
V
CC
(V)
3.3
2.5
3.3
2.5
T
A
=
25°C
Typical
0.8
0.6
−0.8
-0.6
V
V
Units
Capacitance
Symbol
C
IN
C
OUT
C
PD
Input Capacitance
Output Capacitance
Power Dissipation Capacitance
Parameter
Conditions
V
CC
=
Open, V
I
=
0V or V
CC
V
CC
=
3.3V, V
I
=
0V or V
CC
V
CC
=
3.3V, V
I
=
0V or V
CC
, f
=
10 MHz
Typical
7
8
25
Units
pF
pF
pF
www.fairchildsemi.com
4
74LCX157
AC LOADING and WAVEFORMS
Generic for LCX Family
FIGURE 1. AC Test Circuit (C
L
includes probe and jig capacitance)
Test
t
PLH
, t
PHL
t
PZL
, t
PLZ
t
PZH
, t
PHZ
Switch
Open
6V at V
CC
=
3.3
±
0.3V
V
CC
x 2 at V
CC
=
2.5
±
0.2V
GND
Waveform for Inverting and Non-Inverting Functions
编译自semiengineering 业界越来越关注人工智能的功耗问题，但这个问题并没有简单的解决方案。这需要深入了解应用、半导体和系统层面的软件和硬件架构，以及所有这些的设计和实现方式。每个环节都会影响总功耗和提供的效用。这是最终必须做出的权衡。 但首先，必须解决效用问题。电力是否被浪费了？“我们将电力用于有价值的用途，”Ansys（现为新思科技旗下公司）产品营销总监 Marc Swi...[详细]
模拟与混合信号
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
