MM54HC640 MM74HC640 Inverting Octal TRI-STATE Transceiver MM54HC643 MM74HC643
True-Inverting Octal TRI-STATE Transceiver
January 1988
MM54HC640 MM74HC640
Inverting Octal TRI-STATE Transceiver
MM54HC643 MM74HC643
True-Inverting Octal TRI-STATE Transceiver
General Description
These TRI-STATE bi-directional buffers utilize advanced sili-
con-gate CMOS technology and are intended for two-way
asynchronous communication between data buses They
have high drive current outputs which enable high speed
operation even when driving large bus capacitances These
circuits possess the low power consumption and high noise
immunity usually associated with CMOS circuitry yet have
speeds comparable to low power Schottky TTL circuits
Each device has an active low enable G and a direction
control input DIR When DIR is high data flows from the A
inputs to the B outputs When DIR is low data flows from
the B inputs to the A outputs The MM54HC640
MM74HC640 transfers inverted data from one bus to other
and the MM54HC643 MM74HC643 transfers inverted data
from the A bus to the B bus and true data from the B bus to
the A bus
These devices can drive up to 15 LS-TTL Loads and all
inputs are protected from damage due to static discharge by
diodes to V
CC
and ground
Features
Y
Y
Y
Y
Y
Typical propagation delay 13 ns
Wide power supply range 2 鈥?6V
Low quiescent current 80
mA
maximum (74 HC)
TRI-STATE outputs for connection to bus oriented
systems
High output drive 6 mA (min)
Connection Diagrams
Dual-In-Line Package
Dual-In-Line Package
TL F 5344 鈥?1
TL F 5344 鈥?2
Top View
Order Number MM54HC640 or MM74HC640
Top View
Order Number MM54HC643 or MM74HC643
Truth Table
Control
Inputs
G
L
L
H
DIR
L
H
X
640
B data to A bus
A data to B bus
Isolation
Operation
643
B data to A bus
A data to B bus
Isolation
H
e
high level L
e
low level X
e
irrelevant
TRI-STATE is a registered trademark of National Semiconductor Corp
C
1995 National Semiconductor Corporation
TL F 5344
RRD-B30M105 Printed in U S A
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