SN74ALS257ANS

Overview

The SN74ALS257AN is a quad 2-to-1 data selector/multiplexer from the Texas Instruments ALS logic family, housed in a 16-pin PDIP package. It features four independent multiplexers with three-state outputs controlled by an output-enable (OE) input. The device operates within a supply voltage range of 4.5 V to 5.5 V and supports a propagation delay of up to 12 ns. Designed for bus-organized systems, it interfaces directly with system buses without loading data lines when disabled.

Feature Summary

• Provides four independent 2-to-1 data selection paths for multiplexing signals from multiple sources.
• Features three-state outputs that isolate the data lines from the bus when the output-enable input is high.
• Compatible with standard TTL logic levels for direct interface with system buses.

Applications

• Bus-organized systems requiring signal multiplexing
• High-performance systems providing bus interface from multiple sources
• Data selector applications in digital logic circuits

Procurement Notes

Verify the specific ordering suffix 'AN' corresponds to the plastic DIP-16 package configuration. Confirm RoHS compliance status as indicated in the manufacturer's packaging addendum. Ensure the component meets the required operating temperature range of 0°C to 70°C for commercial applications. Cross-reference the datasheet revision date to confirm electrical characteristics match current design requirements.

Selection Notes

Select this component for designs requiring quad 2-to-1 multiplexing with low power consumption typical of the ALS series. Consider the PDIP-16 package for through-hole mounting constraints. Evaluate the 3-state output capability against bus isolation requirements. Compare propagation delays against system timing budgets to ensure signal integrity is maintained across the selected voltage range.

Part Context

This part belongs to the SN54/74ALS257A family of data selectors. It is functionally similar to the SN74ALS258A but differs in output polarity. The ALS series offers faster switching speeds and lower power dissipation compared to standard LS logic families. The device is characterized for commercial temperature ranges, distinct from the military-grade SN54 variants.

Replacement Considerations

SN74ALS258AN serves as a functional substitute with inverted output polarity. SN74AS257AN provides higher drive current and faster switching speeds within the same package. Verify pin compatibility and logic truth tables before substituting to ensure correct signal routing in the existing circuit design.