MM54HC620 MM74HC620 Inverting Octal TRI-STATE Transceiver
MM54HC623 MM74HC623 True Octal TRI-STATE Transceiver
March 1988
MM54HC620 MM74HC620 Inverting
Octal TRI-STATE Transceiver
MM54HC623 MM74HC623 True
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
These devices allow data transmission from the A bus to
the B bus or from the B bus to the A bus depending on the
logic levels at the enable inputs Both buses can be isolated
from each other with proper logic levels at the enable in-
puts When GAB is taken high and GBA is taken low these
devices store the states presently appearing at the data in-
puts The 8-bit codes appearing on the two sets of buses
will be indentical for the 623 option or complimentary for the
620 option
These devices can drive up to 15 LS-TTL loads All inputs
are protected from damage due to static discharge by di-
odes to V
CC
and ground
Features
Y
Y
Y
Y
Y
Typical propagation delays 13 ns
Wide power supply range 2V 鈥?6V
Low quiescent supply current 80
mA
maximum (74HC series)
TRI-STATE outputs for connection to system buses
High output drive 6 mA (minimum)
Connection Diagrams
Dual-In-Line Package
Dual-In-Line Package
TL F 9393 鈥?1
TL F 9393 鈥?2
Top View
Order Number MM54HC623 or MM74HC623
Top View
Order Number MM54HC620 or MM74HC620
Truth Table
Enable Inputs
GBA
L
H
H
L
GAB
L
H
L
L
B data to A bus
A data to B bus
Isolation
B data to A bus
A data to B bus
B data to A bus
A data to B bus
Isolation
B data to A bus
A data to B bus
Operation
TRI-STATE is a registered trademark of National Semiconductor Corporation
C
1995 National Semiconductor Corporation
TL F 9393
RRD-B30M105 Printed in U S A
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