DM74ALS1240A Octal 3-STATE Bus Driver
September 1986
Revised February 2000
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 500Ω 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:
Order Number
DM74ALS1240AWM
Package Number
M20B
Package Description
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
Logic Diagram
Function Table
Input
G
L
L
H
A
L
H
X
Output
Y
H
L
Z
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
© 2000 Fairchild Semiconductor Corporation
DS006261
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DM74ALS1240A
Absolute Maximum Ratings
(Note 1)
Supply Voltage
Input Voltage
Voltage Applied to Disabled Output
Operating Free Air Temperature Range
Storage Temperature Range
Typical
θ
JA
N Package
M Package
60.5°C/W
78.0°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
Operating Free Air Temperature
0
Parameter
Min
4.5
2
0.8
−15
16
70
Typ
5
Max
5.5
Units
V
V
V
mA
mA
°C
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise specified)
Symbol
V
IK
V
OH
Parameter
Input Clamp Voltage
HIGH Level
Output Voltage
V
OL
I
I
I
IH
I
IL
I
O
I
OZH
I
OZL
I
CC
LOW Level
Output Voltage
Input Current at Maximum
Input Voltage
HIGH Level Input Current
LOW Level Input Current
Output Drive Current
HIGH Level 3-STATE
Output Current
LOW Level 3-STATE
Output Current
Supply Current
V
CC
=
5.5V, V
I
=
7V
V
CC
=
5.5V, V
I
=
2.7V
V
CC
=
5.5V, V
IL
=
0.4V
V
CC
=
5.5V, V
O
=
2.25V
V
CC
=
5.5V, V
O
=
2.7V
V
CC
=
5.5V, V
O
=
0.4V
V
CC
=
5.5V
Outputs 3-STATE
Outputs HIGH
Outputs LOW
5
8
8
−30
V
CC
=
4.5V to 5.5V
V
CC
=
4.5V
V
CC
=
4.5V
Conditions
V
CC
=
4.5V, I
I
= −18
mA
I
OH
= −0.4
mA
I
OH
= −3
mA
I
OH
=
Max
I
OL
=
12 mA
I
OL
=
24 mA
V
CC
−
2
2.4
2
0.25
0.35
0.4
0.5
0.1
20
−0.1
−112
20
−20
8
14
13
Min
Typ
Max
−1.2
Units
V
V
V
V
V
V
mA
µA
mA
mA
µA
µA
mA
mA
mA
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DM74ALS1240A
Switching Characteristics
over recommended operating free air temperature range
V
CC
=
4.5V to 5.5V, C
L
=
50 pF,
Symbol
Parameter
From
(Input)
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
Propagation Delay Time
LOW-to-HIGH Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
Output Enable Time
to HIGH Level Output
Output Enable Time
to LOW Level Output
Output Disable Time
from HIGH Level Output
Output Disable Time
from LOW Level Output
G
Y
3
13
ns
G
Y
6
2
22
10
ns
ns
A
Y
2
4
13
20
ns
ns
To
(Output)
R1
=
500Ω, R2
=
500Ω,
T
A
=
Min to Max
Min
2
Max
13
ns
Units
3
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DM74ALS1240A Octal 3-STATE Bus Driver
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.
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