SN74AS646NT Equivalent & Substitute Parts

Part Overview

The SN74AS646NT is a non-inverting transceiver IC manufactured by Texas Instruments, designed for 8-bit data transmission with 3-state output capability. This component operates within a 4.5V to 5.5V supply voltage range and is housed in a 24-pin DIP package for through-hole mounting applications.

The SN74AS646NT carries an obsolete product status. Locating equivalent substitute parts is necessary for ongoing system maintenance, repair, and production continuity when original stock becomes unavailable or when design revisions require alternative packaging configurations.

Substiute Parts

SN74AS646NT

Texas InstrumentsIn Stock: 2107SN74AS646NT Datasheet

Current PartRFQ

SN74AS646DW

Texas InstrumentsIn Stock: 988SN74AS646DW Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74AS646NT is determined by strict equivalence across the following electrical and mechanical parameters:

• Logic type: Non-inverting transceiver configuration
• Functional capacity: 1 element, 8 bits per element
• Output architecture: 3-state output
• Current specifications: 15mA output high, 48mA output low
• Supply voltage range: 4.5V ~ 5.5V
• Operating temperature range: 0°C ~ 70°C
• Base product number: 74AS646
• Compliance certifications: ROHS3, REACH Unaffected

The SN74AS646DW qualifies as a direct functional substitute. Both parts share identical electrical characteristics, logic configuration, and thermal specifications. The primary difference is packaging: the SN74AS646DW uses surface-mount 24-SOIC packaging instead of through-hole 24-DIP, and carries active product status.

Parameter Comparison

Engineering Selection Recommendations

The SN74AS646DW serves as the primary substitute for the obsolete SN74AS646NT. Both components maintain identical electrical performance, functional specifications, and compliance certifications. The SN74AS646DW carries active product status, ensuring continued availability and manufacturing support from Texas Instruments.

Selection between these parts depends on PCB design requirements. The SN74AS646NT requires through-hole mounting on legacy or through-hole-based circuit boards. The SN74AS646DW requires surface-mount assembly capability and is suitable for modern PCB designs utilizing SMD technology.

Both parts satisfy ROHS3 compliance and REACH requirements. MSL rating of 1 (Unlimited) indicates no moisture sensitivity constraints for either component.

Frequently Asked Questions (FAQ)

Q: Can the SN74AS646DW directly replace the SN74AS646NT in existing designs?

A: Electrical substitution is complete. The SN74AS646DW provides identical logic function, output characteristics, and supply voltage specifications. However, physical substitution requires PCB redesign: the SN74AS646NT uses through-hole 24-DIP packaging, while the SN74AS646DW uses surface-mount 24-SOIC packaging. Footprint and assembly method changes are necessary.

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

A: The SN74AS646NT is classified as obsolete, indicating Texas Instruments has discontinued manufacturing and support. The SN74AS646DW maintains active status, ensuring ongoing production, technical support, and long-term availability.

Q: Are there any electrical performance differences between these parts?

A: No. Both components share identical output current specifications (15mA high, 48mA low), supply voltage range (4.5V ~ 5.5V), and operating temperature range (0°C ~ 70°C). Logic configuration and 3-state output behavior are equivalent.

Q: Do both parts meet the same compliance standards?

A: Yes. Both the SN74AS646NT and SN74AS646DW are ROHS3 compliant and REACH unaffected. Moisture sensitivity level is 1 (Unlimited) for both components, indicating no special handling requirements.

Q: What packaging considerations apply to substitution?

A: The SN74AS646NT is a 24-pin DIP package (0.300", 7.62mm) for through-hole mounting. The SN74AS646DW is a 24-pin SOIC package (0.295", 7.50mm width) for surface-mount assembly. Package selection depends on PCB design methodology and assembly capabilities.