74LS640/74F640 IC is an octal transceiver featuring inverting 3-state bus compatible outputs.
The 74F640/74LS640 bus transceivers are designed for asynchronous two-way communication between data buses.
The devices transmit data from the A bus to the B bus or from the B bus to the A bus depending upon the level at the direction control (DIR) input.
The enable input (G) can be used to disable the device so the buses are effectively isolated.
The 74LS6407/4F640 IC has a vast array of working voltage, a wide range of working conditions, and directly interfaces with CMOS, NMOS, and TTL, which allows it to be used in high speed, low noise applications.

What is a Bus Transceiver Circuit?

Bus transceiver circuits are simple electronic tri-state, bi-directional devices that allow the flow of data between two points, making them compatible with bus-oriented systems or the bi-directional (input or output) control of any interface circuitry. A Bus transceiver can be inverting or non-inverting, common examples are 74LS243 & LS242 IC series. They are designed for asynchronous two-way communication between two data buses or input/output devices. The transceiver allows for the transmission of data from the terminal A to terminal B and vice versa depending on the logic level at the direction-control input.

74LS640/74F640 Pinout

74LS640 Pin Configuration

74LS640/74F640 Features & Specifications

• Technology Family: f
• VCC (Min) (V) 4.75
• VCC (Max) (V) 5.25
• Bits (#) 8
• Voltage (Nom) (V) 5
• F @ nom voltage (Max) (MHz) 35
• ICC @ nom voltage (Max) (mA) 0.09
• Propagation delay (Max) (ns) 15
• IOL (Max) (mA) 24
• IOH (Max) (mA) -15
• Rating Catalog
• Operating temperature range (C) 0 to 70
• High-Impedance NPN Base Inputs for Reduced Loading (70 mA in High and Low States)
• Ideal for Applications which Require High-Output Drive and Minimal Bus Loading
• Octal Bidirectional Bus Interface
• 3-State Buffer Outputs Sink 64 mA and Source 15 mA
• ESD Sensitive — 4000 V HBM

Applications

• Usually used in cell phones & other communication devices such as walkie-talkies & CB radios.

You can download this datasheet for 74LS640/74F640 Octal Bus Transceiver IC With Inverting 3-State Outputs from the link given below: