Inverting Octal TRI-STATE Transceiver
Description
MM54HCT640 MM74HCT640 Inverting Octal TRI-STATE Transceiver MM54HCT643 MM74HCT643 True-Inverting Octal TRI-STATE Transceiver
February 1988
MM54HCT640 MM74HCT640 Inverting Octal TRI-STATE Transceiver MM54HCT643 MM74HCT643 True-Inverting Octal TRI-STATE Transceiver
General Description
These TRI-STATE bi-directional transceivers utilize advanced silicon-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 of CMOS circuitry yet have speeds comparable to low power Schottky TTL circuits
All devices are TTL input compatible and can drive up to 15 LS-TTL loads and all inputs are protected from damage due to static discharge by diodes to VCC and ground
Both the MM54HCT640 MM74HCT640 and the MM54HCT643 MM74HCT643 have one active low enable input (G) and a direction control (DIR) When the DIR input is high data flows from the A inputs to the B outputs When DIR is low data flows from B to A The MM54HCT640
MM74HCT640 transfers inverted data from one bus to the other The MM54HCT643 MM74HCT643 transfers inverted data from the A bus to the B bus and non-inverted data from the B bus to the A bus
MM54HCT MM74HCT devices are intended to interface between TTL and NMOS components and standard CMOS devices These parts are also plug-in replacements for LSTTL devices and can be used to reduce power consumption in existing designs
Features
Y TTL input compatible
Y Octal TRI-STATE outputs for mP bus applications 6 mA typical
Y High speed 16 ns typical propagation delay
Y Low power 80 mA maximum (74HCT)
Connection Diagram
Dual-In-Line Packages
TL F 5370 – 1
Top View Order Number MM54HCT640 or MM74HCT640
TL F 5370 – 2
Top View Order Number MM54HCT643 or MM74HCT643
Truth Table
Control Inputs
Operation
G DIR
640
643
L L B data to A bus B data to A bus
L H A data to B bus A data t...
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