MM74HC688WM Equivalent & Substitute Parts

Part Overview

The MM74HC688WM is an 8-bit identity comparator logic IC manufactured by onsemi in a 20-SOIC surface mount package. This device performs magnitude comparison with active low output for the A=B function. The part is currently obsolete, making equivalent substitute parts necessary for ongoing design support, production continuity, and component sourcing flexibility.

Substiute Parts

MM74HC688WM

onsemiIn Stock: 3803MM74HC688WM Datasheet

Current PartRFQ

74HC688D,653

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

SimilarRFQ

CD74HC688M

Harris CorporationIn Stock: 3085CD74HC688M Datasheet

SimilarRFQ

CD74HC688M96

Texas InstrumentsIn Stock: 2916CD74HC688M96 Datasheet

SimilarRFQ

CD74HC688NSR

Texas InstrumentsIn Stock: 4436CD74HC688NSR Datasheet

SimilarRFQ

SN74HC688DWR

Texas InstrumentsIn Stock: 3380SN74HC688DWR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MM74HC688WM is determined by the following critical parameters:

• Functional equivalence: 8-bit identity comparator with A=B active low output
• Electrical compatibility: 2V to 6V supply voltage range, 5.2mA output current capability, 8 µA quiescent current
• Timing performance: Maximum propagation delay specifications at 6V with 50pF load
• Package compatibility: 20-SOIC surface mount package (0.295" width standard)
• Operating temperature range: Minimum -40°C to 85°C support required

All identified substitute parts meet these core substitution criteria. Variations in extended temperature range, product status, and compliance certifications are noted for design consideration but do not disqualify functional equivalence.

Parameter Comparison

Engineering Selection Recommendations

Primary substitutes for active production designs:

• CD74HC688M96 (Texas Instruments): Active product status with ROHS3 compliance. Extended operating temperature range (-55°C to 125°C) provides margin beyond the original specification. Propagation delay of 29ns meets timing requirements. Recommended for new designs requiring long-term component availability.

• CD74HC688NSR (Texas Instruments): Active product status with ROHS3 compliance. Narrower package width (0.209" vs 0.295") requires PCB layout verification for pin-to-pin compatibility, though electrical function remains equivalent. Extended temperature range supported.

• SN74HC688DWR (Texas Instruments): Active product status with ROHS3 compliance. Propagation delay of 36ns is within acceptable range for most applications. Operating temperature matches original specification (-40°C to 85°C). Direct footprint compatibility with MM74HC688WM.

• 74HC688D,653 (Nexperia USA Inc.): Active product status with ROHS3 compliance. Propagation delay of 29ns and extended temperature range (-40°C to 125°C) provide performance margin. Cut Tape & Digi-Reel packaging supports flexible procurement.

Secondary substitute for legacy system support:

• CD74HC688M (Harris Corporation): Obsolete status limits long-term availability. RoHS non-compliant status may conflict with regulatory requirements. Extended temperature range (-55°C to 125°C) and 29ns propagation delay provide functional equivalence for existing designs requiring component replacement only.

Frequently Asked Questions (FAQ)

Q: Can I directly replace MM74HC688WM with any of these substitute parts?

A: All listed substitute parts are functionally equivalent 8-bit identity comparators with identical output function, supply voltage range, output current capability, and quiescent current specifications. Direct replacement is supported from an electrical standpoint. Physical package dimensions should be verified for PCB layout compatibility, particularly for CD74HC688NSR which has a narrower package width.

Q: What is the difference between the various Texas Instruments 74HC688 variants?

A: CD74HC688M96 and CD74HC688NSR differ primarily in package width (0.295" vs 0.209") and propagation delay performance (both 29ns). SN74HC688DWR has a slightly higher propagation delay of 36ns but maintains the standard 0.295" package width. All three are active products with ROHS3 compliance.

Q: Why is the MM74HC688WM obsolete when active alternatives exist?

A: Component obsolescence is determined by the original manufacturer (onsemi) based on market demand and production decisions. Active alternatives from Texas Instruments, Nexperia, and other manufacturers provide equivalent functionality and are recommended for new designs and ongoing production support.

Q: Does operating temperature range affect substitution eligibility?

A: The MM74HC688WM operates from -40°C to 85°C. Substitute parts with extended temperature ranges (-55°C to 125°C) are fully compatible and provide additional thermal margin. Substitutes with identical or narrower temperature ranges remain functionally equivalent for applications within the original specification.

Q: Are there package width considerations for PCB layout?

A: Most substitutes use the standard 0.295" (7.50mm) package width matching the original MM74HC688WM. CD74HC688NSR uses a narrower 0.209" (5.30mm) package width. PCB footprint verification is required before selecting this variant to ensure pin alignment and trace routing compatibility.

Q: What compliance certifications should I consider for new designs?

A: ROHS3 compliance is standard across active substitute parts (CD74HC688M96, CD74HC688NSR, SN74HC688DWR, 74HC688D,653). CD74HC688M is RoHS non-compliant and should be avoided for designs subject to RoHS regulatory requirements. All parts carry REACH Unaffected status where specified.