SN74ALS638A-1DW

Buffers, Drivers, Receivers, Transceivers Overview

The SN74ALS638A-1DW is an octal bus transceiver in a 20-pin Small Outline (DW) package. It facilitates asynchronous two-way communication between open-collector and 3-state buses. The A-bus outputs are open collector, while the B-bus outputs are 3-state. Data transmission direction from A to B or B to A is controlled by the DIR input. The device supports a supply voltage range of 4.5 V to 5.5 V and operates within a temperature range of 0°C to 70°C. Propagation delays vary based on direction and control inputs.

Buffers, Drivers, Receivers, Transceivers Feature Summary

• Bidirectional data transfer capability between open-collector and 3-state buses
• Direction control via dedicated DIR input pin
• Output isolation functionality through OE input

Buffers, Drivers, Receivers, Transceivers Applications

• Asynchronous two-way communication systems
• Interfacing open-collector buses with 3-state logic buses
• Bus transceiver applications requiring direction control

Buffers, Drivers, Receivers, Transceivers Procurement Notes

Verify the specific -1 suffix indicates the increased recommended maximum IOL of 48 mA when VCC is between 4.75 V and 5.25 V. Confirm the DW package designation corresponds to the plastic small-outline format. Ensure the operating environment remains within the specified 0°C to 70°C range for proper characterization.

Buffers, Drivers, Receivers, Transceivers Selection Notes

Select this component when interfacing mixed bus types requiring bidirectional flow. The -1 variant offers higher low-level output current capacity compared to standard versions. Consider the SOIC package dimensions for PCB layout constraints. Verify that the open-collector nature of the A-bus meets system pull-up requirements.

Buffers, Drivers, Receivers, Transceivers Part Context

This device belongs to the Texas Instruments SN74ALS series of octal bus transceivers. It shares functional similarities with the SN74ALS639A but differs in logic polarity. The -1 suffix denotes a specific electrical characteristic modification regarding output current limits. It is part of a family including AS variants with different speed and drive characteristics.

Buffers, Drivers, Receivers, Transceivers FAQ

What is the difference between the SN74ALS638A and SN74ALS638A-1?

The SN74ALS638A-1 version has an increased recommended maximum IOL of 48 mA, applicable only if VCC is between 4.75 V and 5.25 V.

How is the data direction controlled?

Data direction is determined by the logic level at the DIR input. A low level directs data from B to A, while a high level directs data from A to B.