SN74LS42NS

Overview

The SN74LS42NS is a BCD-to-decimal decoder manufactured by Texas Instruments, belonging to the SN74LS logic family. It features four binary-coded decimal inputs and ten active-low outputs, designed to decode valid BCD input states into one of ten distinct output lines. The component operates within a supply voltage range of 4.75 V to 5.25 V and supports through-hole mounting in a standard 16-pin PDIP package. It functions reliably across an operating temperature range from 0°C to +70°C, with a typical propagation delay of 30 ns.

Feature Summary

• Decodes four-bit binary-coded decimal inputs into ten mutually exclusive active-low outputs
• Operates on standard 5V logic supplies within specified tolerance limits
• Provides reliable signal transmission with defined propagation characteristics

Applications

• Display decoding for numeric readouts
• Control logic sequencing in digital systems
• Address decoding for memory or peripheral selection

Procurement Notes

Verify the specific manufacturer source and date code upon receipt to ensure authenticity. Confirm that the physical package matches the 16-pin DIP specification and check for any visible damage to pins or casing. Ensure storage conditions remain within recommended limits to prevent moisture absorption prior to soldering.

Selection Notes

Select this component when a dedicated BCD-to-decimal translation function is required within a TTL-compatible system. Consider the 16-pin DIP package for prototyping or applications requiring manual insertion. Evaluate the 30 ns propagation delay against system timing requirements to ensure adequate performance margins.

Part Context

This device is part of the widely adopted SN74LS series, known for balanced power consumption and speed. It serves as a fundamental building block in legacy and industrial digital electronics where simple decimal decoding is necessary. The LS technology ensures compatibility with other standard logic families while maintaining lower power dissipation compared to earlier variants.

Replacement Considerations

Compatible substitutes include the SN74LS42AN and SN74LS42N. Verify pinout compatibility and electrical specifications before substitution.