DM74AS646WMX Equivalent & Substitute Parts

Part Overview

The DM74AS646WMX is a 24-pin surface mount inverting transceiver IC manufactured by onsemi, designed for 8-bit bidirectional data transfer with 3-state output capability. Operating within a 4.5V to 5.5V supply range, this component belongs to the 74AS logic family and is classified as obsolete. Due to its obsolete status, identifying functionally compatible substitute parts is essential for ongoing system maintenance and new design implementations.

Substiute Parts

DM74AS646WMX

onsemiIn Stock: 1023DM74AS646WMX Datasheet

Current PartRFQ

SN74AS646DW

Texas InstrumentsIn Stock: 988SN74AS646DW Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the DM74AS646WMX is determined by the following critical parameters:

• Series Compatibility: Both parts must belong to the 74AS logic family
• Bit Configuration: 1 element with 8 bits per element
• Output Architecture: 3-state output capability
• Electrical Specifications: Matching output current ratings (15mA high, 48mA low) and supply voltage range (4.5V ~ 5.5V)
• Operating Temperature Range: 0°C ~ 70°C
• Package Footprint: 24-pin SOIC with identical physical dimensions (0.295", 7.50mm width)
• Mounting Technology: Surface mount configuration

The SN74AS646DW qualifies as a substitute based on these parameters. However, the logic inversion characteristic differs: the main part is inverting while the substitute is non-inverting. This functional difference must be evaluated within the context of the specific circuit application.

Parameter Comparison

Engineering Selection Recommendations

The SN74AS646DW from Texas Instruments presents a viable substitute for the obsolete DM74AS646WMX based on electrical and mechanical parameter alignment. The substitute maintains identical output current specifications, supply voltage range, operating temperature range, and physical package dimensions.

The primary distinction is the logic inversion characteristic: the main part performs inverting transceiver functions while the substitute performs non-inverting transceiver functions. Circuit-level evaluation is required to determine whether this functional difference is compatible with the intended application.

The SN74AS646DW carries active product status, ensuring ongoing availability and manufacturing support. The substitute meets ROHS3 compliance requirements, providing environmental and regulatory advantages over the obsolete main part.

Frequently Asked Questions (FAQ)

Q: Can the SN74AS646DW directly replace the DM74AS646WMX without circuit modifications?

A: Physical and electrical parameters are compatible, enabling direct socket substitution. However, the logic inversion difference must be evaluated. If the circuit design accounts for inverting logic, additional signal conditioning may be required when using the non-inverting substitute.

Q: Are the package dimensions identical between these parts?

A: Both parts use 24-SOIC packaging with identical physical dimensions (0.295", 7.50mm width). PCB footprints are compatible.

Q: What is the significance of the product status difference?

A: The DM74AS646WMX is classified as obsolete, indicating discontinued manufacturing and limited availability. The SN74AS646DW maintains active status, ensuring reliable sourcing and continued manufacturer support.

Q: Do both parts have the same moisture sensitivity rating?

A: Yes, both parts carry MSL Level 1 (Unlimited), indicating no moisture sensitivity constraints during storage and handling.

Q: Are there compliance differences between the two parts?

A: The SN74AS646DW is ROHS3 compliant, while the DM74AS646WMX does not specify RoHS compliance. Both parts are REACH unaffected and carry EAR99 ECCN classification.