DM74S257 3-STATE Quad 1-of-2 Data Selector/Multiplexer
August 1986
Revised May 2000
DM74S257
3-STATE Quad 1-of-2 Data Selector/Multiplexer
General Description
These Schottky-clamped high-performance multiplexers
feature 3-STATE outputs that can interface directly with
data lines of bus-organized systems. With all but one of the
common outputs disabled (at a high impedance state), the
low impedance of the single enabled output will drive the
bus line to a HIGH or LOW logic level. To minimize the pos-
sibility that two outputs will attempt to take a common bus
to opposite logic levels, the output enable circuitry is
designed such that the output disable times are shorter
than the output enable times.
This 3-STATE output feature means that n-bit (paralleled)
data selectors with up to 258 sources can be implemented
for data buses. It also permits the use of standard TTL reg-
isters for data retention throughout the system.
Features
s
3-STATE versions S157, S158, with same pin-outs
s
Schottky-clamped for significant improvement in
A-C performance
s
Provides bus interface from multiple sources in high-per-
formance systems
s
Average propagation delay from data input
s
Typical power dissipation
4.8 ns
320 mW
Ordering Code:
Order Number
DM74S257N
Package Number
N16E
Package Description
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Connection Diagram
Function Table
Inputs
Output
Control
H
L
L
L
L
H
=
HIGH Level
L
=
LOW Level
X
=
Don’t Care
Z
=
High Impedance (OFF)
Output
A
X
L
H
X
X
B
X
X
X
L
H
Y
Z
L
H
L
H
Select
X
L
L
H
H
© 2000 Fairchild Semiconductor Corporation
DS006482
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DM74S257
Logic Diagram
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2
DM74S257
Absolute Maximum Ratings
(Note 1)
Supply Voltage
Input Voltage
Operating Free Air Temperature Range
Storage Temperature Range
7V
5.5V
0°C to
+70°C
−65°C
to
+150°C
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 “Recommended Operating Conditions” table will define the conditions
for actual device operation.
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
0
Parameter
Min
4.75
2
0.8
−6.5
20
70
Nom
5
Max
5.25
Units
V
V
V
mA
mA
°C
Electrical Characteristics
over recommended operating free air temperature (unless otherwise noted)
Symbol
V
I
V
OH
V
OL
I
I
I
IH
I
IL
I
OZH
I
OZL
I
OS
I
CCH
I
CCL
I
CCZ
Parameter
Input Clamp Voltage
HIGH Level
Output Voltage
LOW Level
Output Voltage
Input Current @ Max Input Voltage
HIGH Level
Input Current
LOW Level
Input Current
Off-State Output Current with
HIGH Level Output Voltage Applied
Off-State Output Current with
LOW Level Output Voltage Applied
Short Circuit Output Current
Supply Current with Outputs HIGH
Supply Current with Outputs LOW
Supply Current with Outputs Disabled
Conditions
V
CC
=
Min, I
I
= −18
mA
V
CC
=
Min, I
OH
=
Max
V
IL
=
Max, V
IH
=
Min
V
CC
=
Min, I
OL
=
Max
V
IH
=
Min, V
IL
=
Max
V
CC
=
Max, V
I
=
5.5V
V
CC
=
Max
V
I
=
2.7V
V
CC
=
Max,
V
I
=
0.5V
V
CC
=
Max, V
O
=
2.4V
V
IH
=
Min, V
IL
=
Max
V
CC
=
Max, V
O
=
0.5V
V
IH
=
Min, V
IL
=
Max
V
CC
=
Max (Note 3)
V
CC
=
Max (Note 4)
V
CC
=
Max (Note 4)
V
CC
=
Max (Note 4)
−40
44
60
64
Select
Other
Select
Other
0.5
1
100
50
−4
−2
50
−50
−100
68
93
99
2.4
3.2
Min
Typ
(Note 2)
Max
−1.2
Units
V
V
V
mA
µA
mA
µA
µA
mA
mA
mA
mA
Note 2:
All typicals are at V
CC
=
5V, T
A
=
25°C.
Note 3:
Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 4:
I
CC
is measured with all outputs OPEN and all possible inputs grounded, while achieving the stated output conditions.
3
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DM74S257
Switching Characteristics
at V
CC
=
5V and T
A
=
25°C
R
L
=
280Ω
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
Parameter
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Output Enable Time
to HIGH Level Output
Output Enable Time
to LOW Level Output
Output Disable Time
to HIGH Level Output (Note 5)
Output Disable Time
to LOW Level Output (Note 5)
Note 5:
C
L
=
5 pF.
From (Input)
To (Output)
Data to Output
Data to Output
Select to Output
Select to Output
Output Control to Y
Output Control to Y
Output Control to Y
Output Control to Y
C
L
=
15 pF
Min
Max
7.5
6.5
15
15
19.5
21
8.5
14
C
L
=
50 pF
Min
Max
11
10
16
16
23
24
Units
ns
ns
ns
ns
ns
ns
ns
ns
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4
DM74S257 3-STATE Quad 1-of-2 Data Selector/Multiplexer
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
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DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the
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to perform when properly used in accordance with
instructions for use provided in the labeling, can be rea-
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user.
5
2. A critical component in any component of a life support
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sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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