2000 Fairchild Semiconductor Corporation
DS006261
www.fairchildsemi.com
September 1986
Revised February 2000
DM74ALS1240
A
Octal
3-ST
A
T
E
Bus Dri
ver
DM74ALS1240A
Octal 3-STATE Bus Driver
General Description
These octal 3-STATE bus drivers are designed to provide
the designer with flexibility in implementing a bus interface
with memory, microprocessor, or communication systems,
and are low power dissipation versions of the
DM74ALS240A and DM74ALS241A. The output 3-STATE
gating control is organized into two separate groups of four
buffers. The DM74ALS1240A control inputs symmetrically
enable the respective outputs when set logic LOW. The 3-
STATE circuitry contains a feature that maintains the buffer
outputs in 3-STATE (high impedance state) during power
supply ramp-up or ramp-down. This eliminates bus glitch-
ing problems that arise during power-up and power-down.
Features
s
Advanced oxide-isolated, ion-implanted Schottky TTL
process
s
Switching response specified into 500
and 50 pF load
s
Switching response specifications guaranteed over full
temperature and V
CC
supply range
s
PNP input design reduces input loading
s
Low power dissipation version
s
Low level drive current: 74ALS
=
16 mA
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 Logic State
L
=
LOW Level Logic State
X
=
Don't Care (Either LOW or HIGH Level Logic State)
Z
=
High Impedance (OFF) State
Logic Diagram
Order Number
Package Number
Package Description
DM74ALS1240AWM
M20B
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
Input
Output
G
A
Y
L
L
H
L
H
L
H
X
Z
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2
D
M
74ALS124
0A
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 (unless otherwise specified)
Supply Voltage
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
60.5
C/W
M Package
78.0
C/W
Symbol
Parameter
Min
Typ
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
16
mA
T
A
Operating Free Air Temperature
0
70
C
Symbol
Parameter
Conditions
Min
Typ
Max
Units
V
IK
Input Clamp Voltage
V
CC
=
4.5V, I
I
=
-
18 mA
-
1.2
V
V
OH
HIGH Level
V
CC
=
4.5V to 5.5V
I
OH
=
-
0.4 mA
V
CC
-
2
V
Output Voltage
V
CC
=
4.5V
I
OH
=
-
3 mA
2.4
V
I
OH
=
Max
2
V
V
OL
LOW
Level V
CC
=
4.5V
I
OL
=
12 mA
0.25
0.4
V
Output Voltage
I
OL
=
24 mA
0.35
0.5
V
I
I
Input Current at Maximum
V
CC
=
5.5V, V
I
=
7V
0.1
mA
Input Voltage
I
IH
HIGH Level Input Current
V
CC
=
5.5V, V
I
=
2.7V
20
A
I
IL
LOW Level Input Current
V
CC
=
5.5V, V
IL
=
0.4V
-
0.1
mA
I
O
Output Drive Current
V
CC
=
5.5V, V
O
=
2.25V
-
30
-
112
mA
I
OZH
HIGH Level 3-STATE
V
CC
=
5.5V, V
O
=
2.7V
20
A
Output Current
I
OZL
LOW Level 3-STATE
V
CC
=
5.5V, V
O
=
0.4V
-
20
A
Output Current
I
CC
Supply Current
V
CC
=
5.5V
Outputs HIGH
5
8
mA
Outputs LOW
8
14
mA
Outputs 3-STATE
8
13
mA
3
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DM74ALS1240
A
Switching Characteristics
over recommended operating free air temperature range
Symbol
Parameter
V
CC
=
4.5V to 5.5V, C
L
=
50 pF,
Units
From
To
R1
=
500
, R2
=
500
,
(Input)
(Output)
T
A
=
Min to Max
Min
Max
t
PLH
Propagation Delay Time
2
13
ns
LOW-to-HIGH Level Output
A
Y
t
PHL
Propagation Delay Time
2
13
ns
HIGH-to-LOW Level Output
t
PZH
Output Enable Time
4
20
ns
to HIGH Level Output
G
Y
t
PZL
Output Enable Time
6
22
ns
to LOW Level Output
t
PHZ
Output Disable Time
2
10
ns
from HIGH Level Output
G
Y
t
PLZ
Output Disable Time
3
13
ns
from LOW Level Output
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4
DM74ALS1240A
Oct
a
l 3-
ST
A
T
E B
u
s
Dri
ver
Physical Dimensions
inches (millimeters) unless otherwise noted
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
Package Number M20B
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.
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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