SN74ALS638ANS

Buffers, Drivers, Receivers, Transceivers Overview

The SN74ALS638AN is an octal bus transceiver from the Texas Instruments ALS logic family, housed in a standard plastic 20-pin DIP package. It facilitates asynchronous two-way communication between open-collector and 3-state buses. The A-bus outputs are configured as open collector, while the B-bus outputs utilize 3-state logic. Data transmission direction is controlled by the DIR input, allowing transfer from A to B or B to A. An OE input isolates the device when disabled. The component operates within a supply voltage range of 4.5 V to 5.5 V and supports a low-level output current of up to 24 mA.

Buffers, Drivers, Receivers, Transceivers Feature Summary

• Bidirectional data transmission capability between open-collector and 3-state buses
• Direction control via dedicated DIR input for flexible signal routing
• Output isolation feature provided by the OE input pin

Buffers, Drivers, Receivers, Transceivers Applications

• Asynchronous two-way communication interfaces
• Connecting open-collector buses to 3-state buses
• Bus-oriented memory and signal driving applications

Buffers, Drivers, Receivers, Transceivers Procurement Notes

Verify that the specific ordering suffix 'AN' corresponds to the PDIP-20 package variant. Confirm the operating temperature range matches the application requirements, as this part is characterized for operation from 0°C to 70°C. Ensure compatibility with the required supply voltage levels between 4.5 V and 5.5 V before finalizing procurement specifications.

Buffers, Drivers, Receivers, Transceivers Selection Notes

Select this component when designing systems requiring bidirectional data flow between mixed bus types. The open-collector nature of the A-bus allows for wired-AND configurations, while the 3-state B-bus prevents bus contention. Consider the propagation delay characteristics if high-speed switching is critical for the target application architecture.

Buffers, Drivers, Receivers, Transceivers Part Context

This device belongs to the SN74ALS638A series, which includes variants like the SN74ALS639A offering true logic instead of inverting logic. The ALS (Advanced Low-power Schottky) series provides improved speed and power consumption compared to standard TTL. The SN74ALS638AN specifically denotes the through-hole DIP packaging option available from Texas Instruments.

Buffers, Drivers, Receivers, Transceivers Replacement Considerations

SN74ALS639AN serves as a functional substitute if non-inverting logic is required instead of the inverting logic found in the SN74ALS638AN.