SN74LS688DW Equivalent & Substitute Parts

Part Overview

The SN74LS688DW is an 8-bit identity comparator manufactured by Texas Instruments, designed for magnitude comparison applications with active low output. This component is classified as Last Time Buy, indicating discontinued production with limited inventory availability. The identification of equivalent substitute parts is necessary to ensure design continuity and procurement flexibility for applications requiring 8-bit identity comparison functionality with identical electrical and mechanical specifications.

Substiute Parts

SN74LS688DW

Texas InstrumentsIn Stock: 1143SN74LS688DW Datasheet

Current PartRFQ

SN74LS688DWR

Texas InstrumentsIn Stock: 1971SN74LS688DWR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SN74LS688DW is determined by strict equivalence across the following critical parameters:

• Functional Identity: 8-bit identity comparator with A=B output function
• Output Logic: Active low output configuration
• Electrical Specifications: Supply voltage range 4.85V ~ 5.25V, output current ratings 400µA (high) and 24mA (low), propagation delay 23ns @ 5V with 45pF load
• Package Compatibility: 20-SOIC surface mount package with identical physical dimensions (0.295", 7.50mm width)
• Regulatory Compliance: ROHS3 compliant, REACH unaffected status
• Thermal Range: Operating temperature 0°C ~ 70°C

The SN74LS688DWR qualifies as a direct substitute based on identical electrical performance, package specification, and regulatory compliance. The distinction between these parts is limited to packaging format (tube versus tape & reel) and product status classification.

Parameter Comparison

Engineering Selection Recommendations

The SN74LS688DWR is the manufacturer-recommended substitute for the SN74LS688DW. Both components are manufactured by Texas Instruments and maintain identical electrical specifications, functional performance, and package geometry. The SN74LS688DW is designated Last Time Buy status, indicating production discontinuation. The SN74LS688DWR maintains Active product status with higher inventory availability.

Selection between these parts should be based on procurement requirements and packaging format compatibility. The SN74LS688DW is supplied in tube packaging, while the SN74LS688DWR is supplied in tape & reel format. Both parts satisfy ROHS3 compliance and REACH regulatory requirements. No electrical or thermal performance differences exist between these components.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS688DWR directly replace the SN74LS688DW in existing designs?

A: Yes. The SN74LS688DWR is electrically and functionally identical to the SN74LS688DW. Both components feature identical 8-bit identity comparator functionality, active low output configuration, supply voltage range, output current ratings, propagation delay specifications, and 20-SOIC package dimensions. No circuit modifications are required.

Q: What is the difference between tube and tape & reel packaging?

A: Tube packaging (SN74LS688DW) is used for lower-volume orders and manual assembly processes. Tape & reel packaging (SN74LS688DWR) is designed for automated pick-and-place assembly equipment. The components themselves are identical; packaging format selection depends on manufacturing process requirements.

Q: Why is the SN74LS688DW classified as Last Time Buy?

A: Last Time Buy designation indicates that Texas Instruments has discontinued production of this part number. The SN74LS688DWR remains in active production and serves as the recommended alternative for continued procurement.

Q: Are there any compliance or regulatory differences between these parts?

A: No. Both the SN74LS688DW and SN74LS688DWR maintain identical ROHS3 compliance status and REACH unaffected classification. Moisture sensitivity level (MSL 1 - Unlimited) is identical for both components.

Q: What are the critical parameters for substitution compatibility?

A: Substitution compatibility is determined by: 8-bit identity comparator function, active low A=B output, 4.85V ~ 5.25V supply voltage, 400µA/24mA output current ratings, 23ns propagation delay at 5V with 45pF load, 0°C ~ 70°C operating temperature range, and 20-SOIC package specification. The SN74LS688DWR meets all these requirements.