IN74HC640A
OCTAL 3-STATE INVERTING
BUS TRANSCEIVER
High-Performance Silicon-Gate CMOS
The IN74HC640A is identical in pinout to the LS/ALS640. The
device inputs are compatible with standard CMOS outputs; with
pullup resistors, they are compatible with LS/ALSTTL outputs.
The IN74HC640A is a 3-state transceiver that is used for 2-
way asynchronous communication between data buses. The
device has an active-low Output Enable pin, which is used to
place the I/O ports into high-impedance states. The Direction
control determines whether data flows from A to B or from B to A.
• Outputs Directly Interface to CMOS, NMOS, and TTL
• Operating Voltage Range: 2.0 to 6.0 V
ORDERING INFORMATION
• Low Input Current: 1.0 µA
IN74HC640AN Plastic
IN74HC640ADW SOIC
TA = -55° to 125° C for all
packages
• High Noise Immunity Characteristic of CMOS Devices
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Control Inputs
Output
Direction
Operation
PIN 20=VCC
Enable
L
PIN 10 = GND
L
Data Transmitted
from Bus B to Bus
A (inverted)
L
H
X
Data Transmitted
from Bus A to Bus
B (inverted)
H
Buses
Isolated
(High Impedance
State)
X = don’t care
1
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