NSC JM38510-30906BE, JD54LS257SEA, JM38510-30906BF Datasheet
TL/F/6417
54LS257A/DM54LS257B/DM74LS257B, 54LS258A/DM54LS258B/DM74LS258B
TRI-STATE Quad 2-Data Selectors/Multiplexers
June 1989
54LS257A/DM54LS257B/DM74LS257B,
54LS258A/DM54LS258B/DM74LS258B
TRI-STATE
É
Quad 2-Data Selectors/Multiplexers
General Description
These Schottky-clamped high-performance multiplexers
feature TRI-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 TRI-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
Y
TRI-STATE versions LS157 and LS158 with same pinouts
Y
Schottky-clamped for significant improvement in A-C
performance
Y
Provides bus interface from multiple sources in highperformance systems
Y
Average propagation delay from data input 12 ns
Y
Typical power dissipation
LS257B 50 mW
LS258B 35 mW
Y
Alternate military/aerospace devices (54LS257A/
54LS258A) are available. Contact a National Semiconductor Sales Office/Distributor for specifications.
Connection Diagrams
Dual-In-Line Package
TL/F/6417– 1
Order Number 54LS257ADMQB, 54LS257AFMQB,
54LS257ALMQB, DM54LS257BJ, DM54LS257BW,
DM74LS257BM or DM74LS257BN
See NS Package Number E20A, J16A,
M16A, N16E or W16A
Dual-In-Line Package
TL/F/6417– 2
Order Number 54LS258ADMQB, 54LS258AFMQB,
54LS258ALMQB, DM54LS258BJ, DM54LS258BW,
DM74LS258BM or DM74LS258BN
See NS Package Number E20A, J16A,
M16A, N16E or W16A
Function Table
Inputs Output Y
Output
Select A B LS257 LS258
Control
HXXXZZ
LLLXLH
LLHXHL
LHXLLH
LHXHHL
H
e
High Level, LeLow Level, XeDon’t Care,
Z
e
High Impedance (off)
TRI-STATEÉis a registered trademark of National Semiconductor Corporation.
C
1995 National Semiconductor Corporation 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.
Supply Voltage 7V
Input Voltage 7V
Operating Free Air Temperature Range
DM54LS and 54LS
b
55§Ctoa125§C
DM74LS 0
§
Ctoa70§C
Storage Temperature Range
b
65§Ctoa150§C
Note:
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’’
table 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 Parameter
DM54LS257B DM74LS257B
Units
Min Nom Max Min Nom Max
V
CC
Supply Voltage 4.5 5 5.5 4.75 5 5.25 V
V
IH
High Level Input Voltage 2 2 V
V
IL
Low Level Input Voltage 0.7 0.8 V
I
OH
High Level Output Current
b
1
b
2.6 mA
I
OL
Low Level Output Current 12 24 mA
T
A
Free Air Operating Temperature
b
55 125 0 70
§
C
’LS257B Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min
Typ
Max Units
(Note 1)
V
I
Input Clamp Voltage V
CC
e
Min, I
I
eb
18 mA
b
1.5 V
V
OH
High Level Output V
CC
e
Min, I
OH
e
Max DM54 2.4 3.4
V
Voltage V
IL
e
Max, V
IH
e
Min
DM74 2.4 3.1
V
OL
Low Level Output V
CC
e
Min, I
OL
e
Max DM54 0.25 0.4
Voltage V
IL
e
Max, V
IH
e
Min
DM74 0.35 0.5 V
I
OL
e
12 mA, V
CC
e
Min DM74 0.25 0.4
I
I
Input Current@Max V
CC
e
Max, Select 0.2
mA
Input Voltage V
I
e
7V
Other 0.1
I
IH
High Level Input V
CC
e
Max, Select 40
mA
Current V
I
e
2.7V
Other 20
I
IL
Low Level Input V
CC
e
Max, Select
b
0.8
mA
Current V
I
e
0.4V
Other
b
0.4
I
OZH
Off-State Output Current V
CC
e
Max, V
O
e
2.7V
with High Level Output V
IH
e
Min, V
IL
e
Max 20 mA
Voltage Applied
I
OZL
Off-State Output Current V
CC
e
Max, V
O
e
0.4V
with Low Level Output V
IH
e
Min, V
IL
e
Max
b
20 mA
Voltage Applied
I
OS
Short Circuit V
CC
e
Max DM54
b
20
b
100
mA
Output Current (Note 2)
DM74
b
20
b
100
I
CCH
Supply Current with V
CC
e
Max (Note 3)
5.9 10 mA
Outputs High
I
CCL
Supply Current with V
CC
e
Max (Note 3)
9.2 16 mA
Outputs Low
I
CCZ
Supply Current with V
CC
e
Max (Note 3)
12 19 mA
Outputs Disabled
Note 1: All typicals are at V
CC
e
5V, T
A
e
25§C.
Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 3: I
CC
is measured with all outputs open and all possible inputs grounded, while achieving the stated output conditions.
2
’LS257B Switching Characteristics
at V
CC
e
5V and T
A
e
25§C (See Section 1 for Test Waveforms and Output Load)
From (Input)
R
L
e
667X
Symbol Parameter
To (Output)
C
L
e
45 pF C
L
e
150 pF Units
Min Max Min Max
t
PLH
Propagation Delay Time Data to
18 27 ns
Low to High Level Output Output
t
PHL
Propagation Delay Time Data to
18 27 ns
High to Low Level Output Output
t
PLH
Propagation Delay Time Select to
28 35 ns
Low to High Level Output Output
t
PHL
Propagation Delay Time Select to
35 42 ns
High to Low Level Output Output
t
PZH
Output Enable Time Output
15 27 ns
to High Level Output Control to Y
t
PZL
Output Enable Time Output
28 38 ns
to Low Level Output Control to Y
t
PHZ
Output Disable Time from Output
26 ns
High Level Output (Note 1) Control to Y
t
PLZ
Output Disable Time from Output
25 ns
Low Level Output (Note 1) Control to Y
Note 1: C
L
e
5 pF.
Recommended Operating Conditions
Symbol Parameter
DM54LS258B DM74LS258B
Units
Min Nom Max Min Nom Max
V
CC
Supply Voltage 4.5 5 5.5 4.75 5 5.25 V
V
IH
High Level Input Voltage 2 2 V
V
IL
Low Level Input Voltage 0.7 0.8 V
I
OH
High Level Output Current
b
1
b
2.6 mA
I
OL
Low Level Output Current 12 24 mA
T
A
Free Air Operating Temperature
b
55 125 0 70
§
C
’LS258B Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min
Typ
Max Units
(Note 1)
V
I
Input Clamp Voltage V
CC
e
Min, I
I
eb
18 mA
b
1.5 V
V
OH
High Level Output V
CC
e
Min, I
OH
e
Max DM54 2.4 3.4
V
Voltage V
IL
e
Max, V
IH
e
Min
DM74 2.4 3.1
V
OL
Low Level Output V
CC
e
Min, I
OL
e
Max DM54 0.25 0.4
Voltage V
IL
e
Max, V
IH
e
Min
DM74 0.35 0.5 V
I
OL
e
12 mA, V
CC
e
Min DM74 0.25 0.4
I
I
Input Current@Max V
CC
e
Max, Select 0.2
mA
Input Voltage V
I
e
7V
Other 0.1
I
IH
High Level Input V
CC
e
Max, Select 40
mA
Current V
I
e
2.7V
Other 20
3
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