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Fairchild Semiconductor |
October 1986
Revised March 2000
DM74AS640
3-STATE Octal Bus Transceiver
General Description
This advanced Schottky device contains 8 pairs of 3-
STATE logic elements configured as octal bus transceiver.
This circuit is designed for use in memory, microprocessor
systems and in asynchronous bidirectional data buses.
This device transmits data from the A bus to the B bus, or
vice versa, depending upon the logic level of the direction
control input (DIR). The enable input (G) can be used to
disable the devices, effecting isolation of buses A and B.
The 3-STATE circuitry also contains a protection feature
that prevents these transceivers from glitching the bus dur-
ing power-up or power-down.
Features
s Switching specifications at 50 pF
s Switching specifications guaranteed over full tempera-
ture and VCC range
s Advanced oxide-isolated, ion-implanted Schottky TTL
process
s Functionally and pin for pin compatible with Schottky,
low power Schottky, and advanced low power Schottky
TTL counterpart
s Improved AC performance over Schottky, low power
Schottky, and advanced low power Schottky counter-
parts
s 3-STATE outputs independently controlled on A and B
buses
s Low output impedance drive to drive terminated trans-
mission lines to 133Ω
s Specified to interface with CMOS at VOH = VCC − 2V
Ordering Code:
Order Number Package Number
Package Description
DM74AS640WM
M20B
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
DM74AS640N
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
L
H
H = HIGH Logic Level
L = LOW Logic Level
X = Immaterial
H
X
Logic Diagram
Operation
B Data to A Bus
A Data to B Bus
Isolation
Top View
© 2000 Fairchild Semiconductor Corporation DS006708
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Absolute Maximum Ratings(Note 1)
Supply Voltage
7V
Input Voltage
Control Inputs
7V
I/O Ports
5.5V
Operating Free Air Temperature Range 0°C to +70°C
Storage Temperature Range
−65°C to +150°C
Typical θJA
N Package
51.5°C
M Package
69.0°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
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 Max
4.5 5 5.5
2
0.8
−15
64
0 70
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
VI
VOH
VOL
II
IIH
IIL
IO
ICCH
ICCL
ICCZ
Input Clamp Voltage
HIGH Level
Output Voltage
LOW Level Output Voltage
Input Current at Max
Input Voltage
HIGH Level
Input Current
LOW Level
Input Current
Output Drive Current
Supply Current with Outputs HIGH
Supply Current with Outputs LOW
Supply Current with Outputs
in 3-STATE
VCC = Min, II = −18 mA
VCC = 4.5V to 5.5V, IOH = −2 mA
VCC = 4.5V, IOH = −3 mA
VCC = 4.5V, IOH = Max
VCC = Min, IOL = Max
VCC = Max, VI = 7V,
(VI = 5.5V for A or B Ports)
VCC = Max
VI = 2.7V (Note 3)
VCC = Max,
VI = 0.4V (Note 3)
VCC = Max, VO = 2.25V
VCC = Max
Control Inputs
A or B Ports
Control Inputs
A or B Ports
Note 2: All typicals are at VCC = 5.0V, TA = 25°C.
Note 3: For I/O ports, the parameters IIH and IIL include the OFF-State output current, IOZH and IOZL.
Min
VCC − 2
2.4
2.4
−50
Typ
(Note 2)
0.35
37
78
51
Units
V
V
V
mA
mA
°C
Max
−1.2
0.55
0.1
20
70
−0.5
−0.75
−150
58
123
80
Units
V
V
V
V
V
mA
µA
mA
mA
mA
mA
mA
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