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Fairchild Semiconductor |
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 VOH = VCC − 2V
s PNP inputs reduce input loading
s Switching specifications guaranteed over full
temperature and VCC range
Ordering Code:
Order Number Package Number
Package Description
DM74AS245WM
M20B
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
DM74AS245SJ
M20D
20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74AS245N
N20A
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 DIR
LL
LH
HX
Operation
B Data to A Bus
A Data to B Bus
Hi-Z
© 2000 Fairchild Semiconductor Corporation DS006299
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Absolute Maximum Ratings(Note 1)
Supply Voltage, VCC
Input Voltage
Control Inputs
I/O Ports
Operating Free Air Temperature Range
Storage Temperature Range
Typical θJA
N Package
M Package
7V
7V
5.5V
0°C to 70°C
−65°C to +150°C
51.5°C/W
76.0°C/W
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
VCC
VIH
VIL
IOH
IOL
TA
Parameter
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
Min Typ
4.5 5
2
0
Electrical Characteristics
over recommended operating free air temperature range
Symbol
Parameter
Conditions
VIK Input Clamp Voltage
VOH HIGH Level Output
Voltage
VOL LOW Level Output Voltage
II Input Current at Max
Input Voltage
IIH HIGH Level Input Current
IIL LOW Level Input Current
IO Output Drive Current
ICC Supply Current
VCC = 4.5V, IIN = −18 mA
VCC = 4.5V, IOH = −3 mA
VCC = 4.5V, IOH = −15 mA
IOH = −2 mA, VCC = 4.5V to 5.5V
VCC = 4.5V, IOL = Max
VCC = 5.5V, VIN = 7V,
(VIN = 5.5V for A or B Ports)
VCC = 5.5V,
VIN = 2.7V
VCC = 5.5V,
VIN = 0.4V
VCC = 5.5V, VOUT = 2.25V
VCC = 5.5V
Min
2.4
2
VCC − 2
Control Inputs
A or B Ports
Control Inputs
A or B Ports
Output HIGH
Output LOW
3-STATE
−50
Switching Characteristics
over recommended operating free air temperature range
Symbol
Parameter
Conditions
tPLH Propagation Delay Time
HIGH-to-LOW Level Output
tPHL Propagation Delay Time
HIGH-to-LOW Level Output
VCC = 4.5V to 5.5V,
R1 = R2 = 500Ω,
CL = 50 pF
tPZL Output Enable Time to LOW Level
tPZH Output Enable Time to HIGH Level
tPLZ Output Disable Time from LOW Level
tPHZ Output Disable Time from HIGH Level
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
Max
5.5
0.8
−15
48
70
Typ
3.2
2.3
0.35
62
95
79
Min
2
2
2
2
2
2
Units
V
V
V
mA
mA
°C
Max
−1.2
Units
V
V
0.55
0.1
20
70
−0.5
−0.75
−150
97
149
123
V
mA
µA
mA
mA
mA
Max
7.5
7
8.5
9
9.5
5.5
Units
ns
ns
ns
ns
ns
ns
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