DM74AS646WM Equivalent & Substitute Parts

Part Overview

The DM74AS646WM is a 24-pin surface mount inverting transceiver IC manufactured by onsemi, designed for 8-bit data bus applications with 3-state output capability. This component operates within the 4.5V to 5.5V supply voltage range and is rated for 0°C to 70°C operating temperature. The part is currently classified as obsolete, making identification of compatible substitute components essential for ongoing system support and new design implementations.

Substiute Parts

DM74AS646WM

onsemiIn Stock: 873DM74AS646WM Datasheet

Current PartRFQ

SN74AS646DW

Texas InstrumentsIn Stock: 988SN74AS646DW Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the DM74AS646WM is determined by the following critical parameters:

• Series Compatibility: Both parts belong to the 74AS logic family, ensuring functional equivalence within the TTL/CMOS interface standards
• Pin Count and Package: 24-pin SOIC package with identical 0.295" width and 7.50mm physical dimensions
• Electrical Specifications: Matching supply voltage range (4.5V ~ 5.5V), output current ratings (15mA high, 48mA low), and operating temperature range (0°C ~ 70°C)
• Functional Elements: Single element, 8-bit per element configuration with 3-state output capability
• Moisture Sensitivity: MSL Level 1 (Unlimited) classification for both parts

The SN74AS646DW from Texas Instruments meets all substitution criteria. The primary functional difference is the logic inversion characteristic: the DM74AS646WM is inverting while the SN74AS646DW is non-inverting. This distinction must be evaluated against circuit design requirements.

Parameter Comparison

Engineering Selection Recommendations

The SN74AS646DW is the qualified substitute for the DM74AS646WM based on the following factors:

• Product Status: The DM74AS646WM is obsolete, while the SN74AS646DW maintains active production status, ensuring long-term availability and supply chain continuity
• Compliance: The SN74AS646DW carries ROHS3 compliance certification, meeting current environmental and regulatory standards
• Electrical Equivalence: Both parts share identical electrical specifications including supply voltage, output current, and operating temperature ranges
• Physical Compatibility: Identical 24-SOIC package dimensions enable direct PCB footprint compatibility
• Functional Consideration: The inversion logic difference between the two parts requires circuit-level evaluation to determine suitability for specific applications

Frequently Asked Questions (FAQ)

Q: Can the SN74AS646DW directly replace the DM74AS646WM without circuit modifications?

A: Physical and electrical compatibility is confirmed. However, the SN74AS646DW is non-inverting while the DM74AS646WM is inverting. Circuit design must accommodate this functional difference. Direct pin-for-pin substitution is possible only if the application logic accounts for the inversion characteristic change.

Q: Are the package dimensions identical between these parts?

A: Both parts use the 24-SOIC package with 0.295" width and 7.50mm physical dimensions. PCB footprints are identical, enabling direct mounting compatibility.

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

A: The DM74AS646WM is classified as obsolete, indicating discontinued manufacturing. The SN74AS646DW is active production, providing assured availability for current and future procurement.

Q: Do both parts meet current environmental standards?

A: The SN74AS646DW is ROHS3 compliant. Both parts carry MSL Level 1 (Unlimited) moisture sensitivity classification and REACH Unaffected status.

Q: Are the electrical output specifications identical?

A: Output current ratings are identical: 15mA high, 48mA low. Supply voltage range (4.5V ~ 5.5V) and operating temperature range (0°C ~ 70°C) are matched across both parts.