SN74ALS666NT Equivalent & Substitute Parts

Part Overview

The SN74ALS666NT is a D-Type Transparent Latch logic IC manufactured by Texas Instruments, featuring a single 8:8 channel configuration with tri-state output capability. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design support and procurement continuity. The part operates within the 74ALS logic family and is packaged in a 24-pin DIP format suitable for through-hole mounting applications.

Substiute Parts

SN74ALS666NT

Texas InstrumentsIn Stock: 940SN74ALS666NT Datasheet

Current PartRFQ

SN74ALS666DW

Texas InstrumentsIn Stock: 1238SN74ALS666DW Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74ALS666NT is determined by strict equivalence across the following critical parameters:

• Logic Family & Function: Both parts must implement D-Type Transparent Latch logic with identical 8:8 channel configuration
• Electrical Specifications: Voltage supply range, propagation delay, and output current characteristics must match exactly
• Output Architecture: Tri-state output capability is mandatory for functional compatibility
• Operating Conditions: Temperature range and independent circuit count must be identical
• Compliance & Certification: RoHS3 and REACH status must be maintained

The SN74ALS666DW qualifies as a direct substitute based on these parameters. The primary distinction is the packaging format: the original part uses 24-pin DIP (through-hole), while the substitute employs 24-pin SOIC (surface-mount). Both packages maintain identical electrical performance and pin functionality.

Parameter Comparison

Engineering Selection Recommendations

The SN74ALS666DW is the manufacturer-recommended substitute for the obsolete SN74ALS666NT. Both components maintain identical electrical performance, logic functionality, and regulatory compliance status. The transition from through-hole to surface-mount packaging reflects current manufacturing standards and PCB assembly practices.

Selection of the SN74ALS666DW is appropriate for new designs and production continuity. The active product status of the substitute ensures long-term availability and supply chain stability compared to the obsolete original part. Both components satisfy ROHS3 and REACH compliance requirements for regulated markets.

Frequently Asked Questions (FAQ)

Q: Can the SN74ALS666DW directly replace the SN74ALS666NT in existing designs?

A: Electrical and functional replacement is direct. PCB layout modification is required due to packaging format change from 24-DIP (through-hole) to 24-SOIC (surface-mount). Pin functionality and electrical characteristics remain identical.

Q: What is the primary reason for substitution?

A: The SN74ALS666NT is classified as obsolete. The SN74ALS666DW is the active equivalent from the same manufacturer, ensuring continued availability and supply chain support.

Q: Are there compliance differences between the two parts?

A: No. Both parts maintain ROHS3 compliance and REACH unaffected status. Regulatory requirements are satisfied by either component.

Q: What are the package dimension differences?

A: The original 24-DIP package measures 0.300" (7.62mm) in width. The substitute 24-SOIC package measures 0.295" (7.50mm) in width. Both are industry-standard packages with documented pinout compatibility.

Q: Is the propagation delay identical between parts?

A: Yes. Both components specify 6ns propagation delay and identical output current characteristics (400µA high, 8mA low).

Q: Can I use either part interchangeably in my application?

A: Electrical and functional interchangeability is confirmed. Physical board layout changes are necessary to accommodate the different package format.