SN74AS257FN

Overview

The SN74AS257FN is a quad 2-to-1 data selector/multiplexer from the Texas Instruments AS logic series. It features four independent channels, each selecting between two inputs based on a common select line. The device includes three-state outputs controlled by an output enable input, allowing connection to bus systems. It operates within a supply voltage range of 4.5 V to 5.5 V and has a maximum propagation delay of 12 ns. The component is housed in a 16-pin plastic small outline package (NS) and supports through-hole mounting with an operating temperature range of 0°C to +70°C.

Feature Summary

• Provides four independent 2-to-1 data selection paths with shared control inputs for simplified bus interfacing.
• Features three-state outputs that isolate the device from the data bus when disabled, reducing signal loading.
• Delivers high-speed performance characteristic of the AS logic family with low propagation delays.

Applications

• Bus-oriented system data routing
• Data selector circuits in digital instrumentation
• Multiplexing signals for processing

Procurement Notes

Verify the specific suffix 'FN' against official Texas Instruments documentation to confirm the exact package type and tape/reel specifications. Ensure compatibility with existing board layouts regarding pin pitch and thermal requirements. Confirm RoHS compliance status for the specific manufacturing batch prior to integration into final assemblies.

Selection Notes

Select this component when high-speed switching is required alongside standard TTL voltage levels. The AS series offers faster performance than standard 74LS devices while maintaining compatible logic levels. Consider the three-state capability if the design requires sharing a common data bus among multiple sources without external tri-state buffers.

Part Context

This part belongs to the SN74AS257 family of multiplexers. It shares functional similarities with other 74-series selectors but distinguishes itself through the speed advantages of the Advanced Schottky technology. It serves as a direct replacement for slower variants in high-frequency applications where timing margins are critical.

Replacement Considerations

Check for SN74AS257N or SN74AS257D equivalents depending on package preference. Verify pinout compatibility before substituting with SN74S257 or SN74ALS257 variants, as electrical characteristics may differ.