74HCT688N Equivalent & Substitute Parts

Part Overview

The 74HCT688N is an 8-bit identity comparator manufactured by NXP USA Inc., designed to perform magnitude comparison operations with active-low output functionality. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design support and procurement continuity. The 74HCT688 series provides reliable identity comparison in digital logic applications requiring 8-bit parallel data evaluation.

Substiute Parts

74HCT688N,652

NXP USA Inc.In Stock: 92574HCT688N,652 Datasheet

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CD74HCT688E

Texas InstrumentsIn Stock: 2487CD74HCT688E Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74HCT688N is determined by strict equivalence across the following critical parameters:

• Functional Type: Identity Comparator with 8-bit comparison capability
• Output Configuration: Active-low A=B output function
• Electrical Specifications: Supply voltage range 4.5V ~ 5.5V, output current 4mA, propagation delay 34ns @ 4.5V with 50pF load
• Package Format: 20-DIP through-hole mounting (0.300", 7.62mm)
• Quiescent Current: 8 µA maximum
• Compliance: ROHS3 compliant, REACH unaffected

The CD74HCT688E from Texas Instruments meets all substitution criteria, maintaining functional and electrical equivalence while offering active product status and extended operating temperature range.

Parameter Comparison

Engineering Selection Recommendations

The CD74HCT688E represents the direct functional equivalent for 74HCT688N applications. Both components maintain identical electrical specifications and package format, ensuring pin-for-pin compatibility in 20-DIP through-hole implementations.

The CD74HCT688E offers the advantage of active product status from Texas Instruments, providing improved long-term availability and supply chain stability compared to the obsolete 74HCT688N. The extended operating temperature range (-55°C to 125°C versus -40°C to 125°C) provides additional thermal margin for demanding applications.

Both components maintain ROHS3 compliance and REACH unaffected status, satisfying regulatory requirements for current manufacturing standards.

Frequently Asked Questions (FAQ)

Q: Can the CD74HCT688E directly replace the 74HCT688N in existing designs?

A: Yes. The CD74HCT688E is a direct pin-for-pin substitute with identical electrical specifications, output function, and 20-DIP package format. No circuit modifications are required.

Q: What are the key differences between these components?

A: The primary differences are manufacturer (NXP versus Texas Instruments), product status (obsolete versus active), and operating temperature range. The CD74HCT688E supports -55°C to 125°C compared to -40°C to 125°C for the 74HCT688N. All functional and electrical parameters remain identical.

Q: Are there any compliance or certification differences?

A: Both components are ROHS3 compliant and REACH unaffected. No compliance differences exist between the two parts.

Q: What is the significance of the active product status for the CD74HCT688E?

A: Active product status indicates ongoing manufacturing and support from Texas Instruments, ensuring continued availability and supply chain reliability. The obsolete status of the 74HCT688N indicates discontinued production from NXP.

Q: Are the package dimensions identical?

A: Yes. Both components use 20-DIP (0.300", 7.62mm) through-hole packages with identical pin configurations and mechanical specifications.