SN74ALS639ADW

Buffers, Drivers, Receivers, Transceivers Overview

The SN74ALS639ADW is an octal bus transceiver from Texas Instruments, designed for asynchronous two-way communication between open-collector and 3-state buses. It operates within a voltage range of 4.5 V to 5.5 V and features a propagation delay of 10 ns. The device utilizes a 20-pin SOIC (DW) package. A-Bus outputs are configured as open collector, while B-bus outputs are 3-state. It supports both true and inverting logic configurations.

Buffers, Drivers, Receivers, Transceivers Feature Summary

• Supports asynchronous two-way communication between open-collector and 3-state buses
• Features open-collector A-bus outputs and 3-state B-bus outputs
• Available with a choice of true or inverting logic

Buffers, Drivers, Receivers, Transceivers Applications

• Asynchronous data transmission systems
• Interfacing between different bus standards
• High-density digital circuit designs

Buffers, Drivers, Receivers, Transceivers Procurement Notes

Verify the specific suffix 'DW' confirms the 20-pin SOIC package type when ordering. Ensure the design accommodates the open-collector nature of the A-bus outputs, which may require external pull-up resistors depending on the system load. Confirm that the 4.5V to 5.5V operating voltage aligns with the target power supply rails. Check for any specific temperature grade requirements if the application exceeds standard commercial ranges.

Buffers, Drivers, Receivers, Transceivers Selection Notes

Select this component when bidirectional data transfer is required between mixed bus types, specifically involving open-collector lines. The ALS family offers improved speed over standard TTL while maintaining low power consumption. Consider the 20-pin package constraints for PCB layout density. Verify that the 10 ns propagation delay meets the timing requirements of the synchronous or asynchronous interface being implemented.

Buffers, Drivers, Receivers, Transceivers Part Context

This part belongs to the SN74ALS series of high-speed low-power Schottky logic devices. It is functionally compatible with other octal bus transceivers in the 74ALS family, such as the SN74ALS646, though pinouts and specific output configurations may vary. The 'A' marking indicates the specific revision or variant within the manufacturing line.

Buffers, Drivers, Receivers, Transceivers Replacement Considerations

Direct substitutes include other SN74ALS639 variants with different package options, such as SN74ALS639N (PDIP). Cross-family replacements like SN74F646 may offer similar functionality but require verification of voltage levels and output drive capabilities.