DM74AS245 Octal Bus Transceiver with 3-STATE Outputs
October 1986
Revised February 2000
DM74AS245
Octal Bus Transceiver with 3-STATE Outputs
General Description
This advanced Schottky device contains 8 pairs of
3-STATE logic elements configured as octal bus transceiv-
ers. These circuits are designed for use in memory, micro-
processor systems and in asynchronous bidirectional data
buses. Two way communication between buses is con-
trolled by the (DIR) input. Data transmits either from the A
bus to the B bus or from the B bus to the A bus. Both the
driver and receiver outputs can be disabled via the (G)
enable input which causes outputs to enter the high imped-
ance mode so that the buses are effectively isolated.
Features
s
Advanced oxide-isolated, ion-implanted Schottky
TTL process
s
Non-inverting logic output
s
3-STATE outputs independently controlled on
A and B buses
s
Low output impedance to drive terminated transmission
lines to 133Ω
s
Switching response specified into 500Ω/50 pF
s
Specified to interface with CMOS at V
OH
=
V
CC
−
2V
s
PNP inputs reduce input loading
s
Switching specifications guaranteed over full
temperature and V
CC
range
Ordering Code:
Order Number
DM74AS245WM
DM74AS245SJ
DM74AS245N
Package Number
M20B
M20D
N20A
Package Description
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm 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 Diagram
Function Table
Control
Inputs
G
L
L
H
DIR
L
H
X
B Data to A Bus
A Data to B Bus
Hi-Z
Operation
© 2000 Fairchild Semiconductor Corporation
DS006299
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DM74AS245
Absolute Maximum Ratings
(Note 1)
Supply Voltage, V
CC
Input Voltage
Control Inputs
I/O Ports
Operating Free Air Temperature Range
Storage Temperature Range
Typical
θ
JA
N Package
M Package
51.5°C/W
76.0°C/W
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.
7V
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
Typ
5
Max
5.5
Units
V
V
V
mA
mA
°C
Electrical Characteristics
over recommended operating free air temperature range
Symbol
V
IK
V
OH
Parameter
Input Clamp Voltage
HIGH Level Output
Voltage
V
OL
I
I
I
IH
I
IL
I
O
I
CC
LOW Level Output Voltage
Input Current at Max
Input Voltage
HIGH Level Input Current
LOW Level Input Current
Output Drive Current
Supply Current
Conditions
V
CC
=
4.5V, I
IN
= −18
mA
V
CC
=
4.5V, I
OH
= −3
mA
V
CC
=
4.5V, I
OH
= −15
mA
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,
(V
IN
=
5.5V for A or B Ports)
V
CC
=
5.5V,
V
IN
=
2.7V
V
CC
=
5.5V,
V
IN
=
0.4V
V
CC
=
5.5V, V
OUT
=
2.25V
V
CC
=
5.5V
Output HIGH
Output LOW
3-STATE
Control Inputs
A or B Ports
Control Inputs
A or B Ports
−50
62
95
79
2.4
2
V
CC
−
2
0.35
0.55
0.1
20
70
−0.5
−0.75
−150
97
149
123
mA
V
mA
µA
mA
mA
3.2
2.3
V
Min
Typ
Max
−1.2
Units
V
Switching Characteristics
over recommended operating free air temperature range
Symbol
t
PLH
t
PHL
Parameter
Propagation Delay Time
HIGH-to-LOW Level Output
Propagation Delay Time
HIGH-to-LOW Level Output
t
PZL
t
PZH
t
PLZ
t
PHZ
Output Enable Time to LOW Level
Output Enable Time to HIGH Level
Output Disable Time from LOW Level
Output Disable Time from HIGH Level
Conditions
V
CC
=
4.5V to 5.5V,
R
1
=
R
2
=
500Ω,
C
L
=
50 pF
From
A or B
A or B
G
G
G
G
To
B or A
B or A
A or B
A or B
A or B
A or B
Min
2
2
2
2
2
2
Max
7.5
7
8.5
9
9.5
5.5
Units
ns
ns
ns
ns
ns
ns
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2
DM74AS245
Physical Dimensions
inches (millimeters) unless otherwise noted
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
Package Number M20B
3
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DM74AS245
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
Package Number M20D
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4
DM74AS245 Octal Bus Transceiver with 3-STATE Outputs
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.
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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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