CD74HC688M Equivalent & Substitute Parts

Part Overview

The CD74HC688M is an 8-bit identity comparator manufactured by Texas Instruments, designed for magnitude comparison applications with active-low output. This logic IC operates across a 2V to 6V supply range and is housed in a 20-SOIC surface-mount package. The part is currently discontinued at DiGi Electronics, making equivalent substitutes necessary for ongoing production and maintenance applications. Alternative parts must maintain identical functional specifications, electrical characteristics, and package compatibility to ensure direct replacement capability.

Substiute Parts

CD74HC688M

Texas InstrumentsIn Stock: 3126CD74HC688M Datasheet

Current PartRFQ

CD74HC688M96

Texas InstrumentsIn Stock: 2916CD74HC688M96 Datasheet

DirectRFQ

74HC688D,653

Nexperia USA Inc.In Stock: 496474HC688D,653 Datasheet

MFR RecommendedRFQ

74HCT02D,653

Nexperia USA Inc.In Stock: 899474HCT02D,653 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the CD74HC688M is determined by the following critical parameters:

Functional Equivalence Requirements:

• Type: Identity Comparator (8-bit)
• Output Function: A=B with Active Low output
• Number of Bits: 8

Electrical Compatibility Requirements:

• Voltage - Supply: 2V ~ 6V
• Current - Output High, Low: 5.2mA, 5.2mA
• Max Propagation Delay @ V, Max CL: 29ns @ 6V, 50pF
• Current - Quiescent (Iq): 8 µA

Physical & Environmental Requirements:

• Package / Case: 20-SOIC (0.295", 7.50mm Width)
• Mounting Type: Surface Mount
• RoHS Status: ROHS3 Compliant
• Moisture Sensitivity Level (MSL): 1 (Unlimited)

Identified Direct Substitutes:

1. CD74HC688M96 (Texas Instruments) – Identical part with Tape & Reel packaging; meets all electrical and functional specifications; product status Active.

2. 74HC688D,653 (Nexperia USA Inc.) – Manufacturer-recommended equivalent; maintains all core electrical parameters; product status Active; operating temperature range -40°C ~ 125°C (subset of original -55°C ~ 125°C).

Non-Equivalent Part in List:

3. 74HCT02D,653 (Nexperia USA Inc.) – This is a NOR Gate IC with fundamentally different function (4-channel, 2-input NOR logic), different supply voltage range (4.5V ~ 5.5V), and different package (14-SOIC). This part does not qualify as a functional substitute for the CD74HC688M identity comparator.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: CD74HC688M96

The CD74HC688M96 is the direct equivalent from Texas Instruments, maintaining identical electrical specifications, functional characteristics, and operating temperature range. This part is currently Active in product status and available in Tape & Reel packaging format. Selection of this part eliminates any potential compatibility concerns and maintains consistency with the original manufacturer's design.

Secondary Substitute: 74HC688D,653

The 74HC688D,653 from Nexperia USA Inc. is a manufacturer-recommended equivalent that meets all core electrical and functional requirements. This part is Active in product status and available in Cut Tape and Digi-Reel formats. The operating temperature range (-40°C ~ 125°C) is narrower than the original part (-55°C ~ 125°C), making it suitable for applications operating within the -40°C to 125°C envelope. This part is appropriate for standard industrial and commercial temperature environments.

Compliance & Certification:

Both substitute parts maintain ROHS3 compliance, MSL Level 1 (Unlimited), and REACH Unaffected status, ensuring regulatory alignment with the original CD74HC688M.

Frequently Asked Questions (FAQ)

Q: Can the CD74HC688M96 be used as a direct replacement for CD74HC688M?

A: Yes. The CD74HC688M96 is functionally and electrically identical to the CD74HC688M. Both are 8-bit identity comparators with identical supply voltage ranges (2V ~ 6V), output characteristics (5.2mA), propagation delay (29ns @ 6V, 50pF), and package specifications (20-SOIC). The primary difference is packaging format: CD74HC688M is supplied in Tube format, while CD74HC688M96 is supplied in Tape & Reel format.

Q: What is the difference between CD74HC688M96 and 74HC688D,653?

A: Both parts are 8-bit identity comparators with identical electrical specifications and package dimensions (20-SOIC). The key differences are: (1) Manufacturer – CD74HC688M96 is Texas Instruments; 74HC688D,653 is Nexperia USA Inc.; (2) Operating Temperature Range – CD74HC688M96 supports -55°C ~ 125°C; 74HC688D,653 supports -40°C ~ 125°C; (3) Packaging Format – CD74HC688M96 uses Tape & Reel; 74HC688D,653 uses Cut Tape & Digi-Reel. For applications requiring extended low-temperature operation below -40°C, the CD74HC688M96 is required.

Q: Is the 74HCT02D,653 a suitable substitute for the CD74HC688M?

A: No. The 74HCT02D,653 is a NOR Gate IC with fundamentally different functionality. It is a 4-channel, 2-input logic gate, not an 8-bit identity comparator. Additionally, it operates at a different supply voltage range (4.5V ~ 5.5V versus 2V ~ 6V) and uses a different package (14-SOIC versus 20-SOIC). This part is not compatible with CD74HC688M applications.

Q: What packaging formats are available for the substitute parts?

A: CD74HC688M96 is available in Tape & Reel (TR) format, suitable for automated assembly processes. The 74HC688D,653 is available in Cut Tape (CT) and Digi-Reel® formats, also suitable for automated assembly. The original CD74HC688M was supplied in Tube format. All three packaging formats are compatible with standard surface-mount assembly equipment; selection depends on production volume and assembly line requirements.

Q: Are there any temperature range limitations when substituting with 74HC688D,653?

A: The 74HC688D,653 operates across -40°C ~ 125°C, which is a subset of the original CD74HC688M range (-55°C ~ 125°C). If your application requires operation below -40°C, the 74HC688D,653 is not suitable. For applications within the -40°C ~ 125°C range, the 74HC688D,653 is fully compatible.

Q: Do all substitute parts maintain the same RoHS and compliance certifications?

A: Yes. Both CD74HC688M96 and 74HC688D,653 are ROHS3 Compliant, MSL Level 1 (Unlimited), and REACH Unaffected, matching the compliance profile of the original CD74HC688M.