DM74AS257 • DM74AS258 3-STATE Quad 1 of 2 Line Data Selector/Multiplexers
September 1986
Revised March 2000
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:
Order Number
DM74AS257M
DM74AS257N
DM74AS258M
DM74AS258N
Package Number
M16A
N16E
M16A
N16E
Package Description
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
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
Function Table
INPUTS
OUTPUT
SELECT
CONTROL
H
L
L
L
L
X
L
L
H
H
X
L
H
X
X
X
X
X
L
H
Z
L
H
L
H
Z
H
L
H
L
A
B
AS257
AS258
OUTPUT Y
H
=
HIGH Level
L
=
LOW Level
X
=
Don't Care
Z
=
High Impedance (OFF)
© 2000 Fairchild Semiconductor Corporation
DS006107
www.fairchildsemi.com
DM74AS257 • DM74AS258
Absolute Maximum Ratings
(Note 1)
Supply Voltage, V
CC
Input Voltage
Voltage Applied to Disabled Output
Operating Free Air Temperature Range
Storage Temperature Range
Typical
θ
JA
N Package
75.0°C/W
7V
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
4.5
2
0.8
−15
48
70
Nom
5
Max
5.5
Units
V
V
V
mA
mA
°C
Electrical Characteristics
over recommended operating free air temperature range. All typical values are measured at V
CC
=
5V, T
A
=
25°C.
Symbol
V
IK
V
OH
V
OL
I
I
Parameter
Input Clamp
Voltage
HIGH Level
Output Voltage
LOW Level
Output Voltage
Input Current @
Max Input Voltage
I
IH
I
IL
I
O
(Note 2)
I
OZH
I
OZL
I
CCH
I
CCL
I
CCZ
HIGH Level
Input Current
LOW Level
Input Current
Output Drive Current
Off-State Output Current,
HIGH Level Voltage Applied
Off-State Output Current,
LOW Level Voltage Applied
Supply
Current
Supply
Current
Supply
Current
DM74AS257
DM74AS258
DM74AS257
DM74AS258
DM74AS257
DM74AS258
V
CC
=
5.5V
Outputs Open
Outputs Disabled
Outputs LOW
V
CC
=
5.5V, V
O
=
2.25V
V
CC
=
5.5V
V
O
=
2.7V
V
CC
=
5.5V
V
O
=
0.4V
Outputs HIGH
12.9
8.8
19
15.8
19.7
15.5
−50
19.7
13.5
30.6
24.6
31.9
25.2
µA
mA
mA
mA
mA
mA
mA
V
CC
=
5.5V, V
IL
=
0.4V
V
CC
=
5.5V, V
IH
=
2.7V
Conditions
V
CC
=
4.5V, I
I
= −18
mA
V
CC
=
4.5V, I
OH
=
Max
I
OH
= −2
mA, V
CC
=
4.5V to 5.5V
V
CC
=
4.5V, I
OL
=
Max
V
CC
=
5.5V, V
IH
=
7V
A, B, G
Select
A, B, G
Select
Select
All Others
−30
2.4
V
CC
−
2
0.35
0.5
0.1
0.2
20
40
−1
−0.5
−112
−50
3.2
Min
Typ
Max
−1.2
Units
V
V
V
V
mA
µA
mA
mA
µA
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
.
3
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