SN74ALS621AN

Buffers, Drivers, Receivers, Transceivers Overview

The SN74ALS621AN is an octal bus transceiver from the Texas Instruments ALS logic series, designed for asynchronous two-way communication between data buses. It features open-collector true outputs and operates within a supply voltage range of 4.5 V to 5.5 V. The device supports low-level output currents up to 24 mA (or 48 mA for -1 versions) and high-level leakage current of 0.1 mA. Propagation delays range from 5 ns to 33 ns depending on direction and load conditions. It functions in a commercial temperature range of 0°C to 70°C.

Buffers, Drivers, Receivers, Transceivers Feature Summary

• Dual-output-enable configuration allows flexible timing control and local bus-latch capability by simultaneously enabling both directions.
• Open-collector true outputs provide high drive capability suitable for interfacing with various bus loads.
• Non-inverting logic design ensures data transmission integrity from A bus to B bus or vice versa based on enable states.

Buffers, Drivers, Receivers, Transceivers Applications

• Asynchronous two-way communication between data buses
• Local bus-latch applications requiring simultaneous bidirectional data storage
• Bus-oriented memory and I/O systems

Buffers, Drivers, Receivers, Transceivers Procurement Notes

Verify the specific ordering suffix to confirm package type, as 'N' denotes a standard plastic DIP. Confirm whether the '-1' version is required for increased low-level output current specifications. Ensure the component meets RoHS compliance requirements if applicable to the assembly process. Check for any product change notifications regarding material or manufacturing location updates.

Buffers, Drivers, Receivers, Transceivers Selection Notes

Select this component when open-collector outputs are necessary for wired-OR configurations or driving higher voltage loads than the logic supply. The dual-enable feature is critical for designs requiring complex bus arbitration or latch functionality without external flip-flops. Consider the propagation delay limits when designing for high-speed synchronous interfaces.

Buffers, Drivers, Receivers, Transceivers Part Context

This device belongs to the SN74ALS62xA family of octal bus transceivers. It shares functional similarities with the SN74ALS620A (inverting) and SN74ALS623A (three-state), differing primarily in output stage topology. The ALS series offers improved speed-power product compared to standard 74LS logic.

Buffers, Drivers, Receivers, Transceivers Replacement Considerations

SN74ALS620ADW

Buffers, Drivers, Receivers, Transceivers FAQ

What is the difference between SN74ALS621A and SN74ALS621A-1?

The SN74ALS621A-1 version has an increased recommended maximum low-level output current (IOL) of 48 mA, whereas the standard version is rated for 24 mA.

How does the device achieve bus isolation?

Setting either OEAB or OEBA to a high logic level disables the corresponding direction of data flow, effectively isolating the buses from each other.