TLF9393

March 1988

MM54HC620MM74HC620 Inverting

Octal TRI-STATE

Transceiver

MM54HC623MM74HC623 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-

Features

Y

Typical propagation delays 13 ns

Y

Wide power supply range 2V – 6V

Y

Low quiescent supply current 80 mA

maximum (74HC series)

Y

TRI-STATE outputs for connection to system buses

Y

High output drive 6 mA (minimum)

Connection Diagrams

Dual-In-Line Package

TLF9393 – 1

Top View

Order Number MM54HC623 or MM74HC623

Truth Table

Enable Inputs

Operation

GBA

GAB

LL

B data to A bus

B data to A bus

HH

A data to B bus

A data to B bus

H

L

Isolation

Isolation

LL

B data to A bus

B data to A bus

A data to B bus

A data to B bus

Dual-In-Line Package

TLF9393 – 2

Top View

Order Number MM54HC620 or MM74HC620

TRI-STATE

is a registered trademark of National Semiconductor Corporation

C1995 National Semiconductor Corporation

RRD-B30M105Printed in U S A