DM54S251 [NSC]
TRI-STATE 1 of 8 Line Data Selector/Multiplexer; TRI -STATE 1 8号线数据选择器/复用器
| 型号： | DM54S251 |
| 厂家： | 
National Semiconductor |
| 描述： | TRI-STATE 1 of 8 Line Data Selector/Multiplexer |
| 文件： | 总6页 (文件大小：118K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
June 1989
DM54S251/DM74S251 TRI-STATE 1 of 8 Line
É
Data Selector/Multiplexer
General Description
Features
Y
TRI-STATE version of S151
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
Max no. of common outputs
54S 39
Y
74S 129
Y
Y
Typical propagation delay time (D to Y) 8 ns
Typical power dissipation 275 mW
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.
Connection Diagram
Function Table
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
Low Logic Level
H
X
High Logic Level, L
e
e
High Impedance (Off)
Don’t Care, Z
e
D0, D1 . . . D7
The Level of the respective D input
TL/F/6480–1
Order Number DM54S251J or DM74S251N
See NS Package Number J16A or N16E
TRI-STATEÉ is a registered trademark of National Semiconductor Corporation.
C
1995 National Semiconductor Corporation
TL/F/6480
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
5.5V
Operating Free Air Temperature Range
DM54S
DM74S
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
DM54S251
DM74S251
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
0.8
0.8
V
IL
b
b
I
I
2
6.5
20
70
mA
mA
OH
OL
20
b
T
A
55
125
0
C
§
Electrical Characteristics over recommended operating free air temperature (unless otherwise noted)
Typ
Symbol
Parameter
Conditions
Min
Max
Units
(Note 1)
e
e
e b
e
b
1.2
V
V
Input Clamp Voltage
V
Min, I
Min, I
18 mA
V
V
I
CC
I
High Level Output
Voltage
V
V
Max
Min
DM54
DM74
2.4
2.4
3.4
3.2
OH
CC
OH
e
e
Max, V
IL
IH
e
e
V
OL
Low Level Output Voltage
V
V
Min, I
Max
CC
OL
0.5
V
e
e
Min, V
Max
IH
IL
@
Input Current Max
e
e
I
V
Max, V
5.5V
I
CC
I
1
mA
Input Voltage
e
e
e
e
e
I
I
I
High Level Input
Low Level Input Current
V
V
Max, V
Max, V
Max, V
2.7V
0.5V
50
mA
IH
CC
I
b
2
mA
IL
CC
I
e
O
e
Max
Off-State Output Current
with High Level
V
V
2.4
OZH
CC
e
Min, V
IL
50
mA
mA
IH
Output Voltage Applied
e
e
0.5
I
Off-State Output Current
with Low Level
V
V
Max, V
O
OZL
CC
e
e
b
50
Min, V
Max
IH
IL
Output Voltage Applied
e
(Note 2)
b
b
b
I
I
Short Circuit
V
CC
Max
DM54
DM74
40
40
100
100
OS
CC
mA
mA
Output Current
b
e
Supply Current
V
CC
Max (Note 3)
55
85
e
e
25 C.
Note 1: All typicals are at V
5V, T
§
CC
Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 3: I is measured with the outputs open and all inputs at 4.5V.
A
CC
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
L
280X
From (Input)
To (Output)
e
e
L
Symbol
Parameter
C
L
15 pF
C
50 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, or C
PLH
PHL
PLH
PHL
PLH
PHL
PLH
PHL
PZH
PZL
PHZ
PLZ
PZH
PZL
PHZ
PLZ
18
21
23
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
(4 Levels) to Y
Propagation Delay Time
High to Low Level Output
A, B, or C
19.5
15
13.5
12
12
7
(4 Levels) to Y
Propagation Delay Time
Low to High Level Output
A, B, or C
18
(3 Levels) to W
Propagation Delay Time
High to Low Level Output
A, B, or C
17
(3 Levels) to W
Propagation Delay Time
Low to High Level Output
D to Y
D to Y
D to W
D to W
15
Propagation Delay Time
High to Low Level Output
15
Propagation Delay Time
Low to High Level Output
10
Propagation Delay Time
High to Low Level Output
7
10
Output Enable Time
to High Level Output
Strobe
to Y
19.5
21
Output Enable Time
to Low Level Output
Strobe
to Y
Output Disable Time
Strobe
to Y
8.5
14
to High Level Output (Note 1)
Output Disable Time
Strobe
to Y
to Low Level Output (Note 1)
Output Enable Time
to High Level Output
Strobe
to W
19.5
21
Output Enable Time
to Low Level Output
Strobe
to W
Output Disable Time
Strobe
to W
8.5
14
to High Level Output (Note 1)
Output Disable Time
Strobe
to W
to Low Level Output (Note 1)
e
Note 1: C
5 pF.
L
3
Logic Diagram
TL/F/6480–2
4
Physical Dimensions inches (millimeters)
16-Lead Ceramic Dual-In-Line Package (J)
Order Number DM54S251J
NS Package Number J16A
5
Physical Dimensions inches (millimeters) (Continued)
16-Lead Molded Dual-In-Line Package (N)
Order Number DM74S251N
NS Package Number N16E
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with instructions for use provided in the labeling, can
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to the user.
2. A critical component is any component of a life
support device or system whose failure to perform can
be reasonably expected to cause the failure of the life
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