© 2000 Fairchild Semiconductor Corporation
DS006107
www.fairchildsemi.com
September 1986
Revised March 2000
DM74AS257
·
DM74AS258 3-ST
A
T
E
Quad 1 of 2
Li
ne Data Sele
ctor
/Mult
i
p
lexer
s
DM74AS257 · DM74AS258
3-STATE Quad 1 of 2 Line Data Selector/Multiplexers
General Description
These data selectors/multiplexers contain inverters and
drivers to supply full on-chip data selection to the four 3-
STATE outputs that can interface directly with data lines of
bus-organized systems. A 4-bit word selected from one of
two sources is routed to the four outputs. The DM74AS257
presents true data whereas the DM74AS258 presents
inverted data to minimize propagation delay time.
This 3-STATE output feature means that n-bit (paralleled)
data selectors with up to 300 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
Switching specifications at 50 pF
s
Switching specifications guaranteed over full tempera-
ture and V
CC
range
s
Advanced oxide-isolated, ion-implanted Schottky TTL
process
s
Functionally and pin for pin compatible with Schottky,
low power Schottky, and advanced low power Schottky
TTL counterpart
s
Improved AC performance over Schottky, low power
Schottky, and advanced low power Schottky counter-
parts
s
3-STATE buffer-type output drive bus lines directly
s
Expand any data input point
s
Multiplex dual data buses
s
General four functions of two variables (one variable is
common)
s
Source programmable counters
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Connection Diagram
Function Table
H
=
HIGH Level
L
=
LOW Level
X
=
Don't Care
Z
=
High Impedance (OFF)
Order Number
Package Number
Package Description
DM74AS257M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74AS257N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
DM74AS258M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74AS258N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
INPUTS
OUTPUT Y
OUTPUT
SELECT
A
B
AS257
AS258
CONTROL
H
X
X
X
Z
Z
L
L
L
X
L
H
L
L
H
X
H
L
L
H
X
L
L
H
L
H
X
H
H
L
3
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DM74AS257
· DM74AS258
Absolute Maximum Ratings
(Note 1)
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
Electrical Characteristics
over recommended operating free air temperature range. All typical values are measured at V
CC
=
5V, T
A
=
25
°
C.
Note 2: The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, I
OS
.
Supply Voltage, V
CC
7V
Input Voltage
7V
Voltage Applied to Disabled Output
5.5V
Operating Free Air Temperature Range
0
°
C to
+
70
°
C
Storage Temperature Range
-
65
°
C to
+
150
°
C
Typical
JA
N Package
75.0
°
C/W
Symbol
Parameter
Min
Nom
Max
Units
V
CC
Supply Voltage
4.5
5
5.5
V
V
IH
HIGH Level Input Voltage
2
V
V
IL
LOW Level Input Voltage
0.8
V
I
OH
HIGH Level Output Current
-
15
mA
I
OL
LOW Level Output Current
48
mA
T
A
Free Air Operating Temperature
0
70
°
C
Symbol
Parameter
Conditions
Min
Typ
Max
Units
V
IK
Input Clamp
V
CC
=
4.5V, I
I
=
-
18 mA
-
1.2
V
Voltage
V
OH
HIGH Level
V
CC
=
4.5V, I
OH
=
Max
2.4
3.2
V
Output Voltage
I
OH
=
-
2 mA, V
CC
=
4.5V to 5.5V
V
CC
-
2
V
V
OL
LOW Level
V
CC
=
4.5V, I
OL
=
Max
0.35
0.5
V
Output Voltage
I
I
Input Current @
V
CC
=
5.5V, V
IH
=
7V
A, B, G
0.1
mA
Max Input Voltage
Select
0.2
I
IH
HIGH Level
V
CC
=
5.5V, V
IH
=
2.7V
A, B, G
20
µ
A
Input Current
Select
40
I
IL
LOW
Level V
CC
=
5.5V, V
IL
=
0.4V
Select
-
1
mA
Input Current
All Others
-
0.5
I
O
(Note 2)
Output Drive Current
V
CC
=
5.5V, V
O
=
2.25V
-
30
-
112
mA
I
OZH
Off-State Output Current,
V
CC
=
5.5V
-
50
µ
A
HIGH Level Voltage Applied
V
O
=
2.7V
I
OZL
Off-State Output Current,
V
CC
=
5.5V
-
50
µ
A
LOW Level Voltage Applied
V
O
=
0.4V
I
CCH
Supply
DM74AS257
Outputs HIGH
12.9
19.7
mA
Current
DM74AS258
8.8
13.5
mA
I
CCL
Supply
DM74AS257
V
CC
=
5.5V
Outputs LOW
19
30.6
mA
Current
DM74AS258
Outputs Open
15.8
24.6
mA
I
CCZ
Supply
DM74AS257
Outputs Disabled
19.7
31.9
mA
Current
DM74AS258
15.5
25.2
mA
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4
DM
74AS257
· DM
74AS258
DM74AS257 Switching Characteristics
over recommended operating free air temperature range
DM74AS258 Switching Characteristics
over recommended operating free air temperature range
Symbol
Parameter
From
To
Conditions
Min
Max
Units
t
PLH
Propagation Delay Time,
Data
Any
V
CC
=
4.5V to 5.5V,
1
5.5
ns
LOW-to-HIGH Level Output
Y
C
L
=
50 pF,
t
PHL
Propagation Delay Time,
R
L
=
500
1
6
ns
HIGH-to-LOW Level Output
t
PLH
Propagation Delay Time,
Select
Any
2
11
ns
LOW-to-HIGH Level Output
Y
t
PHL
Propagation Delay Time,
2
10
ns
HIGH-to-LOW Level Output
t
PZH
Output Enable Time to
OUTPUT
Any
2
7.5
ns
HIGH Level
Control
Y
t
PZL
Output Enable Time to
2
9.5
ns
LOW Level
t
PHZ
Output Disable Time,
OUTPUT
Any
1.5
6.5
ns
from HIGH Level
Control
Y
t
PLZ
Output Disable Time,
2
7
ns
from LOW Level
Symbol
Parameter
From
To
Conditions
Min
Max
Units
t
PLH
Propagation Delay Time,
Data
Any
V
CC
=
4.5V to 5.5V,
1
5
ns
LOW-to-HIGH Level Output
Y
C
L
=
50 pF,
t
PHL
Propagation Delay Time,
R
L
=
500
1
4
ns
HIGH-to-LOW Level Output
t
PLH
Propagation Delay Time,
Select
Any
2
9.5
ns
LOW-to-HIGH Level Output
Y
t
PHL
Propagation Delay Time,
2
10
ns
HIGH-to-LOW Level Output
t
PZH
Output Enable Time to
OUTPUT
Any
2
8
ns
HIGH Level
Control
Y
t
PZL
Output Enable Time to
2
10
ns
LOW Level
t
PHZ
Output Disable Time,
OUTPUT
Any
1.5
6
ns
from HIGH Level
Control
Y
t
PLZ
Output Disable Time,
2
6.5
ns
from LOW Level
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