Fairchild DM74LS257B 3-state quad 2-data selectors/multiplexer Datasheet

Revised November 1999
DM74LS257B
3-STATE Quad 2-Data Selectors/Multiplexers
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 possibility 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 registers for data retention throughout the system.
Features
■ 3-STATE versions LS157 and LS158 with same pinouts
■ Schottky-clamped for significant improvement in A-C
performance
■ Provides bus interface from multiple sources in
high-performance systems
■ Average propagation delay from data input 12 ns
■ Typical power dissipation: 50 mW
Ordering Code:
Order Number
Package Number
Package Description
DM74LS257BM
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS257BN
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
Logic Diagram
Function Table
Inputs
Output
Output Y
Select
A
B
LS257
H
X
L
L
X
X
Z
L
X
L
L
L
H
X
H
L
H
X
L
L
L
H
X
H
H
Control
H = HIGH Level
L = LOW Level
X = Don’t Care
Z = High Impedance (off)
© 1999 Fairchild Semiconductor Corporation
DS006417
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DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers
June 1989
DM74LS257B
Absolute Maximum Ratings(Note 1)
Supply Voltage
7V
Input Voltage
7V
0°C to +70°C
Operating Free Air Temperature Range
Storage Temperature Range
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.
−65°C to +150°C
Recommended Operating Conditions
Symbol
Parameter
Min
Nom
Max
Units
VCC
Supply Voltage
4.75
5
5.25
V
VIH
HIGH Level Input Voltage
VIL
LOW Level Input Voltage
0.8
V
IOH
HIGH Level Output Current
−2.6
mA
IOL
LOW Level Output Current
24
mA
TA
Free Air Operating Temperature
70
°C
2
V
0
DC Electrical Characteristics
Symbol
Parameter
Conditions
VI
Input Clamp Voltage
VCC = Min, II = −18 mA
VOH
HIGH Level Output Voltage
VIL = Max, VIH = Min
VOL
II
IIH
IIL
IOZH
IOZL
Min
Typ
(Note 2)
Max
−1.5
2.4
3.1
LOW Level Output
VIL = Max, VIH = Min
0.35
0.5
IOL = 12 mA, VCC = Min
0.25
0.4
Input Current @ Max
VCC = Max,
Select
0.2
Input Voltage
VI = 7V
Other
0.1
HIGH Level Input
VCC = Max,
Select
40
Current
VI = 2.7V
Other
20
LOW Level Input
VCC = Max,
Select
−0.8
Current
VI = 0.4V
Other
−0.4
OFF-State Output Current with
VCC = Max, VO = 2.7V
HIGH Level Output Voltage Applied
VIH = Min, VIL = Max
OFF-State Output Current with
VCC = Max, VO = 0.4V
LOW Level Output Voltage Applied
VIH = Min, VIL = Max
Short Circuit Output Current
VCC = Max (Note 3)
ICCH
Supply Current with Outputs HIGH
VCC = Max (Note 4)
ICCL
Supply Current with Outputs LOW
VCC = Max (Note 4)
ICCZ
Supply Current with Outputs Disabled VCC = Max (Note 4)
20
mA
µA
mA
µA
−20
µA
mA
5.9
10
mA
9.2
16
mA
12
19
mA
Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 4: ICC is measured with all outputs open and all possible inputs grounded, while achieving the stated output conditions.
2
V
−100
−20
Note 2: All typicals are at VCC = 5V, TA = 25°C.
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V
V
Voltage
IOS
Units
VCC = 5V and TA = 25°C
RL = 667Ω
Symbol
Parameter
CL = 45 pF
From (Input)
To (Output)
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPZH
Output Enable Time
to HIGH Level Output
tPZL
Output Enable Time
to LOW Level Output
tPHZ
Output Disable Time from
HIGH Level Output (Note 5)
tPLZ
Output Disable Time from
LOW Level Output (Note 5)
Min
CL = 150 pF
Max
Min
Units
Max
Data to Output
18
27
ns
Data to Output
18
27
ns
Select to Output
28
35
ns
Select to Output
35
42
ns
Output Control to Y
15
27
ns
Output Control to Y
28
38
ns
Output Control to Y
28
ns
Output Control to Y
25
ns
Note 5: CL = 5 pF
3
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DM74LS257B
Switching Characteristics
DM74LS257B
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
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DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
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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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD
SEMICONDUCTOR CORPORATION. As used herein:
2. A critical component in any component of a life support
device or system whose failure to perform can be reasonably expected to cause the failure of the life support
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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 reasonably expected to result in a significant injury to the
user.
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