DM74LS251J [NSC]
IC,LOGIC MUX,SINGLE,8-INPUT,LS-TTL,DIP,16PIN,CERAMIC;
| 型号： | DM74LS251J |
| 厂家： | 
National Semiconductor |
| 描述： | IC,LOGIC MUX,SINGLE,8-INPUT,LS-TTL,DIP,16PIN,CERAMIC 复用器 |
| 文件： | 总6页 (文件大小：138K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
June 1989
DM54LS251/DM74LS251
TRI-STATE Data Selectors/Multiplexers
É
General Description
Features
Y
TRI-STATE version of LS151
These data selectors/multiplexers contain full on-chip bina-
ry decoding to select one-of-eight data sources, and feature
a strobe-controlled TRI-STATE output. The strobe must be
at a low logic level to enable these devices. The TRI-STATE
outputs permit direct connection to a common bus. When
the strobe input is high, both outputs are in a high-imped-
ance state in which both the upper and lower transistors of
each totem-pole output are off, and the output neither drives
nor loads the bus significantly. When the strobe is low, the
outputs are activated and operate as standard TTL totem-
pole outputs.
Y
Interface directly with system bus
Y
Perform parallel-to-serial conversion
Y
Permit multiplexing from N-lines to one line
Y
Complementary outputs provide true and inverted data
Maximum number of common outputs
54LS 49
Y
Y
Y
74LS 129
Typical propagation delay time (D to Y)
54LS 17 ns
74LS 17 ns
To minimize the possibility that two outputs will attempt to
take a common bus to opposite logic levels, the output con-
trol circuitry is designed so that the average output disable
time is shorter than the average output enable time.
Typical power dissipation
54LS 35 mW
74LS 35 mW
Connection Diagram
Function Table
Dual-In-Line Package
Inputs
Select
Outputs
Strobe
S
Y
W
C
B
A
X
L
X
L
X
L
H
L
L
L
L
L
L
L
L
Z
Z
D0
D1
D2
D3
D4
D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
L
L
H
L
L
H
H
L
L
H
L
H
H
H
H
L
H
L
H
H
H
e
e
e
H
X
High Logic Level, L
Low Logic Level,
e
Don’t Care, Z
High Impedance (Off)
e
D0, D1 . . . D7
The level of the respective D input
TL/F/6415–1
Order Number DM54LS251J, DM54LS251W,
DM74LS251M or DM74LS251N
See NS Package Number J16A, M16A, N16E or W16A
TRI-STATEÉ is a registered trademark of National Semiconductor Corporation.
C
1995 National Semiconductor Corporation
TL/F/6415
RRD-B30M105/Printed in U. S. A.
Absolute Maximum Ratings (Note)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Note: The ‘‘Absolute Maximum Ratings’’ are those values
beyond which the safety of the device cannot be guaran-
teed. The device should not be operated at these limits. The
parametric values defined in the ‘‘Electrical Characteristics’’
table are not guaranteed at the absolute maximum ratings.
The ‘‘Recommended Operating Conditions’’ table will define
the conditions for actual device operation.
Supply Voltage
Input Voltage
7V
7V
Operating Free Air Temperature Range
DM54LS
DM74LS
b
b
a
55 C to 125 C
§
0 C to 70 C
§
a
§
§
a
65 C to 150 C
Storage Temperature Range
§
§
Recommended Operating Conditions
DM54LS251
DM74LS251
Symbol
Parameter
Units
Min
4.5
2
Nom
Max
Min
4.75
2
Nom
Max
V
V
V
Supply Voltage
5
5.5
5
5.25
V
V
CC
High Level Input Voltage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Free Air Operating Temperature
IH
0.7
0.8
V
IL
b
b
I
I
1
2.6
24
70
mA
mA
OH
OL
12
b
T
A
55
125
0
C
§
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
Typ
Symbol
Parameter
Conditions
Min
Max
Units
(Note 1)
e
e
e b
e
b
1.5
V
V
Input Clamp Voltage
V
Min, I
Min, I
18 mA
V
I
CC
I
High Level Output
Voltage
V
V
Max
Min
DM54
DM74
DM54
DM74
DM74
2.4
2.4
3.4
3.1
OH
CC
OH
V
e
e
Max, V
IL
IH
e
e
e
V
OL
Low Level Output
Voltage
V
V
Min, I
Max
Min
0.25
0.35
0.25
0.4
CC
OL
e
Max, V
IH
IL
0.5
0.4
V
e
e
I
12 mA, V
Min
OL
CC
@
Input Current Max
e
e
I
V
Max, V
7V
I
CC
I
0.1
20
mA
Input Voltage
e
e
e
e
e
I
I
I
High Level Input Current
Low Level Input Current
V
V
Max, V
Max, V
Max, V
2.7V
0.4V
mA
IH
CC
I
b
0.4
mA
IL
CC
I
e
Off-State Output Current
with High Level Output
Voltage Applied
V
V
2.7V
OZH
CC
O
e
e
Min, V
IL
Max
20
mA
IH
e
Max, V
e
I
I
Off-State Output Current
with Low Level Output
Voltage Applied
V
V
0.4V
OZL
OS
CC
O
e
e
b
20
Min, V
Max
mA
IH
IL
e
(Note 2)
b
b
b
Short Circuit
V
CC
Max
DM54
DM74
20
20
100
100
mA
Output Current
b
e
e
I
I
Supply Current
Supply Current
V
V
Max (Note 3)
Max (Note 4)
6.1
7.1
10
12
mA
mA
CC1
CC2
CC
CC
e
e
25 C.
Note 1: All typicals are at V
5V, T
§
Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.
CC
A
Note 3: I
Note 4: I
is measured with the outputs open, STROBE grounded, and all other inputs at 4.5V.
is measured with the outputs open and all inputs at 4.5V.
CC1
CC2
2
e
e
25 C (See Section 1 for Test Waveforms and Output Load)
Switching Characteristics at V
5V and T
§
CC
A
e
R
667X
L
From (Input)
to (Output)
e
e
L
Symbol
Parameter
C
L
45 pF
C
150 pF
Max
Units
Min
Max
Min
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
Propagation Delay Time
Low to High Level Output
A, B, C
(4 Levels) to Y
PLH
PHL
PLH
PHL
PLH
PHL
PLH
PHL
PZH
PZL
PHZ
PLZ
PZH
PZL
PHZ
PLZ
45
53
53
38
42
35
38
25
25
60
51
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Propagation Delay Time
High to Low Level Output
A, B, C
(4 Levels) to Y
45
33
33
28
28
15
15
45
40
45
25
27
40
55
25
Propagation Delay Time
Low to High Level Output
A, B, C
(3 Levels) to W
Propagation Delay Time
High to Low Level Output
A, B, C
(3 Levels) to W
Propagation Delay Time
Low to High Level Output
D
to Y
Propagation Delay Time
High to Low Level Output
D
to Y
Propagation Delay Time
Low to High Level Output
D
to W
Propagation Delay Time
High to Low Level Output
D
to W
Output Enable Time to
High Level Output
Strobe
to Y
Output Enable Time to
Low Level Output
Strobe
to Y
Output Disable Time from
High Level Output (Note 1)
Strobe
to Y
Output Disable Time from
Low Level Output (Note 1)
Strobe
to Y
Output Enable Time to
High Level Output
Strobe
to W
40
47
Output Enable Time to
Low Level Output
Strobe
to W
Output Disable Time from
High Level Output (Note 1)
Strobe
to W
Output Disable Time from
Low Level Output (Note 1)
Strobe
to W
e
Note 1: C
5 pF
L
Logic Diagram
TL/F/6415–2
3
Physical Dimensions inches (millimeters)
16-Lead Ceramic Dual-In-Line Package (J)
Order Number DM54LS251J
NS Package Number J16A
4
Physical Dimensions inches (millimeters) (Continued)
16-Lead Small Outline Molded Package (M)
Order Number DM74LS251M
NS Package Number M16A
Molded Dual-In-Line Package (N)
Order Number DM74LS251N
NS Package Number N16E
5
Physical Dimensions inches (millimeters) (Continued)
16-Lead Ceramic Flat Package (W)
Order Number DM54LS251W
NS Package Number W16A
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