SN74LS157N [MOTOROLA]
QUAD 2-INPUT MULTIPLEXER; 四2输入多路复用器
| 型号： | SN74LS157N |
| 厂家： | 
MOTOROLA |
| 描述： | QUAD 2-INPUT MULTIPLEXER |
| 文件： | 总5页 (文件大小：162K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SN54/74LS157
QUAD 2-INPUT MULTIPLEXER
The LSTTL/MSI SN54/74LS157 is a high speed Quad 2-Input Multiplexer.
Four bits of data from two sources can be selected using the common Select
and Enable inputs. The four buffered outputs present the selected data in the
true (non-inverted) form. The LS157 can also be used to generate any four
of the 16 different functions of two variables. The LS157 is fabricated with the
Schottky barrier diode process for high speed and is completely compatible
with all Motorola TTL families.
QUAD 2-INPUT MULTIPLEXER
LOW POWER SCHOTTKY
• Schottky Process for High Speed
• Multifunction Capability
• Non-Inverting Outputs
• Input Clamp Diodes Limit High Speed Termination Effects
• Special Circuitry Ensures Glitch Free Multiplexing
• ESD > 3500 Volts
J SUFFIX
CERAMIC
CONNECTION DIAGRAM DIP (TOP VIEW)
CASE 620-09
16
1
NOTE:
The Flatpak version has
the same pinouts
(Connection Diagram) as
the Dual In-Line Package.
N SUFFIX
PLASTIC
CASE 648-08
16
1
PIN NAMES
LOADING (Note a)
HIGH LOW
0.5 U.L.
D SUFFIX
SOIC
CASE 751B-03
S
E
Common Select Input
1.0 U.L.
1.0 U.L.
0.5 U.L.
0.5 U.L.
10 U.L.
16
Enable (Active LOW) Input
Data Inputs from Source 0
Data Inputs from Source 1
Multiplexer Outputs (Note b)
0.5 U.L.
0.25 U.L.
0.25 U.L.
1
I
–I
–I
0a 0d
I
1a 1d
Z –Z
a
5 (2.5) U.L.
ORDERING INFORMATION
d
NOTES:
SN54LSXXXJ Ceramic
SN74LSXXXN Plastic
SN74LSXXXD SOIC
a) 1 TTL Unit Load (U.L.) = 40 µA HIGH/1.6 mA LOW.
b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)
Temperature Ranges.
LOGIC DIAGRAM
LOGIC SYMBOL
FAST AND LS TTL DATA
5-268
SN54/74LS157
FUNCTIONAL DESCRIPTION
The LS157 is a Quad 2-Input Multiplexer fabricated with the
Schottky barrier diode process for high speed. It selects four
bits of data from two sources under the control of a common
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 LS157 is the logic implementation of a 4-pole,
2-position switch where the position of the switch is deter-
minedbythelogiclevelssuppliedtotheSelectInput. Thelogic
equations for the outputs are:
Z = E (I
1a
S + I
S)
S)
Z = E (I
S + I
S + I
S)
S)
a
0a
b
1b
1d
0b
0d
Z
= E (I
1c
S + I
Z = E (I
d
c
0c
A common use of the LS157 is the moving of data from two
groups of registers to four common output busses. The partic-
ular register from which the data comes is determined by the
state of the Select Input. A less obvious use is as a function
generator. TheLS157cangenerateanyfourof the16different
functions of two variables with one variable common. This is
useful for implementing highly irregular logic.
TRUTH TABLE
SELECT
INPUT
ENABLE
INPUTS
OUTPUT
E
S
I
0
I
1
Z
H
L
L
L
L
X
H
H
L
X
X
X
L
X
L
H
X
X
L
L
H
L
L
H
H
H = HIGH Voltage Level
L = LOW Voltage Level
X = Don’t Care
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
V
CC
Supply Voltage
54
74
4.5
4.75
5.0
5.0
5.5
5.25
V
T
A
Operating Ambient Temperature Range
54
74
–55
0
25
25
125
70
°C
I
I
Output Current — High
Output Current — Low
54, 74
–0.4
mA
mA
OH
54
74
4.0
8.0
OL
FAST AND LS TTL DATA
5-269
SN54/74LS157
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits
Symbol
Parameter
Input HIGH Voltage
Unit
Test Conditions
Min
Typ
Max
Guaranteed Input HIGH Voltage for
All Inputs
V
2.0
V
IH
54
74
0.7
0.8
Guaranteed Input LOW Voltage for
All Inputs
V
V
V
Input LOW Voltage
V
IL
Input Clamp Diode Voltage
Output HIGH Voltage
–0.65
3.5
–1.5
V
V
V
V
V
= MIN, I = –18 mA
IN
IK
CC
54
74
2.5
2.7
= MIN, I
OH
= MAX, V = V
IN
CC
IH
OH
or V per Truth Table
IL
3.5
V
V
= V
CC
MIN,
= V or V
IL IH
54, 74
74
0.25
0.35
0.4
0.5
V
V
I
= 4.0 mA
= 8.0 mA
CC
IN
OL
OL
V
OL
Output LOW Voltage
I
per Truth Table
Input HIGH Current
I , I
E, S
20
40
µA
mA
mA
V
CC
V
CC
V
CC
= MAX, V = 2.7 V
IN
0
1
I
I
IH
I , I
E, S
0.1
0.2
0
1
= MAX, V = 7.0 V
IN
Input LOW Current
I , I
–0.4
–0.8
= MAX, V = 0.4 V
IN
0
1
IL
E, S
I
I
Short Circuit Current (Note 1)
Power Supply Current
–20
–100
16
mA
mA
V
V
= MAX
= MAX
OS
CC
CC
CC
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (T = 25°C)
A
Limits
Typ
Symbol
Parameter
Propagation Delay
Unit
Test Conditions
Min
Max
t
t
9.0
9.0
14
14
PLH
PHL
ns
Figure 2
Figure 1
Figure 2
Data to Output
V = 5.0 V
CC
= 15 pF
t
t
Propagation Delay
Enable to Output
13
14
20
21
PLH
PHL
ns
ns
C
L
t
t
Propagation Delay
Select to Output
15
18
23
27
PLH
PHL
AC WAVEFORMS
Figure 1
Figure 2
FAST AND LS TTL DATA
5-270
Case 751B-03 D Suffix
16-Pin Plastic
SO-16
-A-
16
1
9
8
P
C
-B-
R X 45°
G
-T-
J
M
F
D
°
°
°
°
K
Case 648-08 N Suffix
16-Pin Plastic
-A-
16
1
9
B
S
8
F
L
C
K
-T-
M
H
J
G
D
°
°
°
°
Case 620-09 J Suffix
16-Pin Ceramic Dual In-Line
-A-
16
9
-B-
1
8
L
C
-T-
K
M
N
E
J
F
G
D
°
°
°
°
FAST AND LS TTL DATA
5-271
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