DM74AS240 • DM74AS244 3-STATE Bus Driver/Receiver
October 1986
Revised March 2000
DM74AS240 • DM74AS244
3-STATE Bus Driver/Receiver
General Description
This family of Advance Schottky 3-STATE Bus circuits are
designed to provide either bidirectional or unidirectional
buffer interface in Memory, Microprocessor, and Communi-
cation Systems. The output characteristics of the circuits
have low impedance sufficient to drive terminated trans-
mission lines down to 133Ω. The input characteristics of
the circuits likewise have a high impedance so it will not
significantly load the transmission line. The package con-
tains eight 3-STATE buffers organized with four buffers
having a common 3-STATE enable gate. The DM74AS240
and DM74AS244 are eight wide in a 20 pin package, and
may be used as a 4 wide bidirectional or eight wide unidi-
rectional. The buffer selection includes inverting and non-
inverting, with enable or disable 3-STATE control.
Features
s
Advanced oxide-isolated, ion-implanted Schottky TTL
process
s
Improved switching performance with less power dissi-
pation compared with Schottky counterpart
s
Functional and pin compatible with 74LS and Schottky
counterpart
s
Switching response specified into 500Ω and 50 pF
s
Specified to interface with CMOS at V
OH
=
V
CC
−
2V
Ordering Code:
Order Number
DM74AS240WM
DM74AS240N
DM74AS244WM
DM74AS244N
Package Number
M20B
N20A
M20B
N20A
Package Description
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
20-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 Diagrams
DM74AS240
DM74AS244
Function Tables
DM74AS240
Inputs
G
L
L
H
A
L
H
X
Output
Y
H
L
Z
H
=
HIGH Logic Level
DM74AS244
Inputs
G
L
L
H
X
=
Either LOW or HIGH Logic Level
Output
A
L
H
X
Y
L
H
Z
L
=
LOW Logic Level
Z
=
High Impedance
© 2000 Fairchild Semiconductor Corporation
DS006298
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DM74AS240 • DM74AS244
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
M Package
57.0°C/W
76.0°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
64
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
Parameter
Input Clamp Voltage
HIGH Level
Output Voltage
V
OL
I
I
I
IH
I
IL
LOW Level Output Voltage
Input Current at Max Input Voltage
HIGH Level Input Current
LOW Level Input Current
Conditions
V
CC
=
4.5V, I
IN
= −18
mA
V
CC
=
4.5V, I
OH
= −3
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
IN
=
7V
Others
Others
AS240, (G, G),
(Control Inputs),
DM74AS244 (G)
DM74AS244 (A)
I
OZH
I
OZL
I
O
(Note 2)
I
CC
HIGH Level 3-STATE Output Current V
CC
=
5.5V, V= 2.7V
LOW Level 3-STATE
Output Current
Output Drive Current
DM74AS240
Supply Current
I
CC
DM74AS244
Supply Current
V
CC
=
5.5V
V
CC
=
5.5V, V
=
0.4V
V
CC
=
5.5V, V
OUT
=
2.25V
V
CC
=
5.5V
Outputs HIGH
Outputs LOW
3-STATE
Outputs HIGH
Outputs LOW
3-STATE
DM74AS240,
DM74AS244
−50
−115
11
51
24
22
60
34
−1000
50
−50
−150
17
75
38
34
90
54
mA
mA
µA
µA
mA
−500
µA
V
CC
=
5.5V, V
IN
=
2.7V
V
CC
=
5.5V, V
IN
=
0.4V
2.4
2.4
V
CC
−2
0.35
0.55
100
20
V
µA
µA
3.2
V
Min
Typ
Max
−1.2
Units
V
Note 2:
The output conditions have been chosen to produce a current that closely approximates one half the true short-circuit output current, I
OS
.
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2
DM74AS240 • DM74AS244
DM74AS240 Switching Characteristics
over recommended operating free air temperature range
Symbol
t
PLH
t
PHL
Parameter
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
t
PZL
t
PZH
t
PLZ
t
PHZ
Output Enable to LOW Level
Output Enable to HIGH Level
Output Disable from LOW Level
Output Disable from HIGH Level
Conditions
V
CC
=
4.5V to 5.5V
R
1
=
R
2
=
500Ω
C
L
=
50 pF
From
(Input)
A
A
G
G
G
G
To
(Output)
Y
Y
Y
Y
Y
Y
Min
2
2
2
2
2
2
Max
6.5
5.7
9
6.4
9.5
5
Units
ns
ns
ns
ns
ns
ns
DM74AS244 Switching Characteristics
over recommended operating free air temperature range
Symbol
t
PLH
t
PHL
t
PZL
t
PZH
t
PLZ
t
PHZ
Parameter
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Output Enable to LOW Level
Output Enable to HIGH Level
Output Disable from LOW Level
Output Disable from HIGH Level
Conditions
V
CC
=
4.5V to 5.5V
R
1
=
R
2
=
500Ω
C
L
=
50 pF
From
(Input)
A
A
G
G
G
G
To
(Output)
Y
Y
Y
Y
Y
Y
Min
2
2
2
2
2
2
Max
6.2
6.2
7.5
9
9
6
Units
ns
ns
ns
ns
ns
ns
3
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DM74AS240 • DM74AS244
Physical Dimensions
inches (millimeters) unless otherwise noted
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
Package Number M20B
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4
DM74AS240 • DM74AS244 3-STATE Bus Driver/Receiver
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Package Number N20A
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.
LIFE SUPPORT POLICY
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:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the
body, or (b) support or sustain life, and (c) whose failure
to perform when properly used in accordance with
instructions for use provided in the labeling, can be rea-
sonably expected to result in a significant injury to the
user.
5
2. A critical component in any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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