SN74ALS259D

Overview

The SN74ALS259D is an 8-bit addressable latch from the Texas Instruments ALS logic family, housed in a 16-pin Small-Outline (SOIC) package. It operates on a supply voltage between 4.5 V and 5.5 V with a standard operating temperature range of 0°C to 70°C. The device features asynchronous parallel clear, active-high decoding capabilities, and four distinct functional modes: addressable latch, memory, demultiplexer, and clear. Electrical characteristics include a low-level output current of up to 8 mA and propagation delays ranging from 2 ns to 26 ns depending on the input-to-output path.

Feature Summary

• Provides eight individually addressable storage latches for general-purpose digital data retention
• Functions as an active-high decoder or 1-of-8 demultiplexer with selectable outputs
• Includes an asynchronous parallel clear input to force all outputs to a low state instantly
• Features an enable/disable input that simplifies system expansion and prevents erroneous data entry

Applications

• Working registers within digital processing systems
• Serial-to-parallel conversion circuits
• Active-high decoding applications
• Demultiplexing signal distribution networks

Procurement Notes

Verify the specific ordering suffix to confirm the package type and production status, as the 'D' suffix indicates a plastic small-outline package. Confirm RoHS compliance and lead finish details via the manufacturer's packaging addendum. Ensure the selected variant matches the required commercial temperature range of 0°C to 70°C rather than the military grade version.

Selection Notes

Select this component when eight individually addressable storage locations are required within a single integrated circuit. It is suitable for designs needing active-high decoding or demultiplexing functions alongside data storage. Verify that the system operates within the specified 4.5 V to 5.5 V supply voltage range and requires TTL-compatible inputs.

Part Context

This device belongs to the Texas Instruments SN74ALS series, which utilizes Advanced Low-Power Schottky technology to achieve higher speed and lower power consumption compared to standard LS logic. The SN74ALS259D specifically denotes the commercial grade version packaged in a surface-mount SOIC format, distinct from the military-grade SN54ALS259J.

Replacement Considerations

SN74ALS259DR

FAQ

How does the device handle data during the memory mode?

In memory mode, all latches retain their previous states regardless of changes to the data or address inputs, provided the enable input remains high.

What is the function of the asynchronous clear input?

The asynchronous clear input forces all eight outputs to a low state immediately, independent of the clock, address, or data inputs.