74640 (74LS640) (Octal Bus Transceiver IC With Inverting 3-State Outputs)

74LS640 is a low-power Schottky octal inverting bus transceiver with 3-state outputs, designed for asynchronous two-way data communication between data buses. It is a standard component in the 74LS family of logic ICs, typically available in a 20-pin DIP package. 

Key Features and Specifications

According to Texas Instruments and Motorola datasheets, the 74LS640 has the following features:

• Function: Octal (8-bit) bidirectional bus transceiver for two-way communication between data buses.
• Output Polarity: The outputs are inverting, meaning the data transmitted is logically inverted from the input.
• Outputs: Features 3-state outputs which allow multiple devices to be connected to the same bus line, providing effective isolation when the device is disabled.
• Control Inputs: The operation is controlled by two inputs: a Direction Control (DIR) input and an Output Enable (G) input.
• Voltage: Operates on a nominal supply voltage (VCC) of 5V, with a recommended range of 4.75V to 5.25V.
• Noise Margin: Hysteresis at the bus inputs improves noise margins, enhancing performance in noisy environments.
• Speed: Offers fast switching, with a typical propagation delay of 15 ns. 

Applications

The 74LS640 is ideal for applications requiring high-output drive and minimal bus loading. 

• Bus Interfacing: Used to connect and isolate data buses in digital systems.
• Memory Interface: Functions as a driver/receiver for memory addressing and data lines.
• Computer Systems: Utilized in computer systems and peripherals for parallel data transfer and port expansion. 

Datasheet

https://www.alldatasheet.com/datasheet-pdf/view/5745/MOTOROLA/74LS640.html