74HCT688D,652 Equivalent & Substitute Parts

Part Overview

The 74HCT688D,652 is an 8-bit identity comparator manufactured by NXP Semiconductors, designed for magnitude comparison applications with active-low output. This device is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The CD74HCT688M96 from Texas Instruments serves as a direct functional equivalent with enhanced availability and active product status.

Substiute Parts

74HCT688D,652

NXP SemiconductorsIn Stock: 75074HCT688D,652 Datasheet

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CD74HCT688M96

Texas InstrumentsIn Stock: 2969CD74HCT688M96 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

The CD74HCT688M96 qualifies as a direct substitute for the 74HCT688D,652 based on the following critical parameters:

• Functional Equivalence: Both devices are 8-bit identity comparators with identical output function (A=B) and active-low output configuration
• Electrical Compatibility: Identical supply voltage range (4.5V ~ 5.5V), output current ratings (4mA high/low), propagation delay (34ns @ 4.5V, 50pF), and quiescent current (8µA)
• Package Compatibility: Both use 20-SOIC packaging with identical physical dimensions (0.295", 7.50mm width), enabling direct PCB footprint compatibility
• Compliance Alignment: Both devices maintain ROHS3 compliance, REACH unaffected status, and identical moisture sensitivity level (MSL 1)
• Series Continuity: Both belong to the 74HCT logic series with base product number 74HCT688

Parameter Comparison

Engineering Selection Recommendations

The CD74HCT688M96 is the appropriate substitute for the obsolete 74HCT688D,652. Selection is based on:

• Product Status: The CD74HCT688M96 maintains active product status with established supply chains, whereas the 74HCT688D,652 is obsolete and subject to availability constraints
• Regulatory Compliance: Both devices maintain identical ROHS3 and REACH compliance certifications, ensuring regulatory continuity in applications
• Extended Temperature Range: The CD74HCT688M96 provides an extended lower operating temperature limit (-55°C vs -40°C), offering broader environmental compatibility without compromising upper temperature performance
• Functional Parity: Electrical and timing characteristics are identical across all critical parameters, enabling direct substitution without circuit redesign

Frequently Asked Questions (FAQ)

Q: Can the CD74HCT688M96 replace the 74HCT688D,652 in existing designs?

A: Yes. Both devices are 8-bit identity comparators with identical electrical specifications, output characteristics, and 20-SOIC packaging. Direct substitution is possible without circuit modifications.

Q: Are there package compatibility concerns?

A: No. Both devices use 20-SOIC packaging with identical physical dimensions (0.295", 7.50mm width). PCB footprints are directly compatible.

Q: What is the difference in operating temperature range?

A: The CD74HCT688M96 operates from -55°C to 125°C, while the 74HCT688D,652 operates from -40°C to 125°C. The extended lower temperature range of the substitute provides additional environmental flexibility.

Q: Are compliance certifications maintained with substitution?

A: Yes. Both devices are ROHS3 compliant and REACH unaffected, maintaining identical regulatory status.

Q: What are the key electrical parameters that determine substitution eligibility?

A: Supply voltage (4.5V ~ 5.5V), output current (4mA), propagation delay (34ns @ 4.5V, 50pF), and quiescent current (8µA) must match. Both devices meet these criteria.