SN74LS257BN

Overview

The SN74LS257BN is a quad 2-line to 1-line data selector/multiplexer from the Texas Instruments 74LS series. It features true outputs and three-state capability for bus-oriented systems. The device operates on a single power supply with a voltage range of 4.75V to 5.25V. It utilizes a 16-pin plastic dual in-line package (PDIP) designed for through-hole mounting. The component supports standard TTL logic levels and functions as a high-speed low-power Schottky logic device.

Feature Summary

• Provides four independent multiplexing channels for routing data signals
• Features three-state outputs to prevent bus loading when disabled
• Delivers true output polarity matching input selection states

Applications

• Bus-oriented memory addressing systems
• Data routing in digital communication interfaces
• Signal selection in test and measurement equipment

Procurement Notes

Verify the manufacturer marking matches Texas Instruments or authorized licensees such as NXP, as legacy parts may carry different branding. Confirm the package type is strictly PDIP-16 plastic. Check RoHS compliance status as original LS series parts may not meet current environmental directives. Ensure the part number suffix 'BN' corresponds to the specific tape-and-reel or tube packaging variant required for your assembly process.

Selection Notes

Select this component when designing with standard 5V TTL logic families requiring moderate speed and low power consumption. It serves as a direct functional replacement for other 74LS257 variants across manufacturers. Consider the 16-pin DIP footprint constraints during PCB layout. Evaluate propagation delay specifications against system timing requirements if higher speed is needed.

Part Context

This part belongs to the widely adopted 7400-series logic family, specifically the Low-power Schottky (LS) subset. It is a legacy component often found in industrial control and older computing hardware. While newer CMOS technologies offer lower power, this TTL-based device remains relevant for compatibility with existing 5V designs.

Replacement Considerations

The SN74LS257BN is directly replaceable by the SN74LS257BN manufactured by Texas Instruments. Other compatible equivalents include the DM74LS257BN from onsemi. Verify pinout compatibility before substitution.