DM74AS257MX

Overview

The DM74AS257MX is a 3-STATE Quad 1 of 2 Line Data Selector/Multiplexer manufactured by onsemi. It operates within a supply voltage range of 4.5 V to 5.5 V and features an SOIC-16 package. The device provides four independent multiplexing circuits, routing true data from two sources to three-state outputs. Propagation delay times are specified at 15 ns (LOW-to-HIGH) and 16 ns (HIGH-to-LOW) for data inputs, with select input delays up to 21 ns. Operating temperatures range from 0°C to +70°C.

Feature Summary

• Features 3-STATE outputs capable of directly interfacing with bus-organized system data lines.
• Utilizes advanced oxide-isolated, ion-implanted Schottky TTL process technology.
• Functionally and pin-for-pin compatible with standard Schottky, low power Schottky, and advanced low power Schottky TTL counterparts.

Applications

• Implementing n-bit paralleled data selectors for data buses.
• Multiplexing dual data buses in digital systems.
• Routing 4-bit words from multiple sources to common output lines.

Procurement Notes

Verify the specific ordering suffix 'X' indicates tape and reel packaging as per manufacturer documentation. Confirm that the component is sourced from authorized channels due to its status as a legacy product. Ensure compatibility with existing 5V logic designs before procurement, as this device belongs to the AS logic family requiring strict voltage adherence.

Selection Notes

Select the DM74AS257MX when true data output is required, distinguishing it from the inverted DM74AS258 variant. This component is suitable for applications needing direct bus interfacing via 3-STATE outputs. Consider the 5V operating requirement and Schottky speed characteristics. Verify package availability in SOIC-16 format if surface mount installation is necessary for the target design.

Part Context

This component belongs to the DM74AS series of high-speed Schottky TTL logic devices originally developed by Fairchild Semiconductor. The series is characterized by improved AC performance over standard Schottky counterparts. The DM74AS257 specifically addresses data selection needs in bus-oriented architectures, providing reliable signal routing with defined propagation delays.

Replacement Considerations

Public confirmed substitute part number: SN74AS257D (Texas Instruments).

FAQ

What is the difference between the DM74AS257 and DM74AS258?

The DM74AS257 presents true data to the outputs, whereas the DM74AS258 presents inverted data to minimize propagation delay time.

Can the outputs be used directly on a bus?

Yes, the 3-STATE buffer-type output drive allows the device to interface directly with data lines of bus-organized systems.