74HC688DB,112 Equivalent & Substitute Parts

Part Overview

The 74HC688DB,112 is an 8-bit identity magnitude comparator manufactured by Nexperia USA Inc., designed for logic-level comparison applications requiring active-low output signaling. This component operates across a 2V to 6V supply voltage range and delivers A=B output functionality in a 20-SSOP surface-mount package.

The 74HC688DB,112 is classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs, repairs, and system upgrades.

Substiute Parts

74HC688DB,112

Nexperia USA Inc.In Stock: 85074HC688DB,112 Datasheet

Current PartRFQ

CD74HC688PWR

Texas InstrumentsIn Stock: 2903CD74HC688PWR Datasheet

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CD74HC688PWT

Texas InstrumentsIn Stock: 1696CD74HC688PWT Datasheet

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SN74HC688PWR

Texas InstrumentsIn Stock: 1913SN74HC688PWR Datasheet

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SN74HC688PWT

Texas InstrumentsIn Stock: 1254SN74HC688PWT Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74HC688DB,112 is determined by the following critical parameters:

• Functional equivalence: 8-bit identity comparator with A=B output function and active-low output configuration
• Electrical compatibility: Supply voltage range 2V ~ 6V, output current 5.2mA (high and low), quiescent current 8 µA
• Timing specifications: Maximum propagation delay at 6V with 50pF load
• Package compatibility: Surface-mount packages (20-SSOP or 20-TSSOP variants)
• Regulatory compliance: ROHS3 compliance, REACH unaffected status, MSL Level 1

Substitute parts must maintain identical functional behavior, electrical performance within specified tolerances, and regulatory compliance. Package variants (SSOP vs. TSSOP) are acceptable substitutes provided they meet electrical and thermal specifications.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Active Product Status):

CD74HC688PWR and SN74HC688PWR are the preferred substitutes for the obsolete 74HC688DB,112. Both are manufactured by Texas Instruments and maintain active product status, ensuring long-term availability and supply chain continuity.

CD74HC688PWR offers extended operating temperature range (-55°C ~ 125°C) compared to the original part (-40°C ~ 125°C), providing broader thermal coverage. This part is supplied in Tape & Reel packaging and maintains the 29ns propagation delay specification.

SN74HC688PWR is supplied in Cut Tape & Digi-Reel packaging and operates within -40°C ~ 85°C temperature range. This part exhibits 36ns propagation delay, which remains within acceptable margins for most logic-level comparison applications.

Secondary Substitutes (Discontinued Status):

CD74HC688PWT and SN74HC688PWT are discontinued at DiGi Electronics but remain available through alternative distribution channels. These parts are functionally equivalent to their active counterparts but should be selected only when primary substitutes are unavailable.

Package Consideration:

All Texas Instruments substitutes use 20-TSSOP packaging (0.173", 4.40mm width) versus the original 20-SSOP packaging (0.209", 5.30mm width). TSSOP packages are physically smaller and require PCB layout adjustment. Verify PCB footprint compatibility before design implementation.

Regulatory Compliance:

All substitute parts maintain ROHS3 compliance and REACH unaffected status, meeting current environmental and regulatory requirements equivalent to the original component.

Frequently Asked Questions (FAQ)

Q: Can I directly replace 74HC688DB,112 with CD74HC688PWR or SN74HC688PWR without circuit modification?

A: Electrical substitution is direct. However, package geometry differs: the original uses 20-SSOP (5.30mm width) while substitutes use 20-TSSOP (4.40mm width). PCB footprint modification is required. Verify pin-to-pin compatibility and adjust solder pad dimensions accordingly.

Q: What is the difference between CD74HC688PWR and SN74HC688PWR?

A: Both are Texas Instruments 8-bit identity comparators with identical functional specifications. CD74HC688PWR operates across -55°C ~ 125°C with 29ns propagation delay. SN74HC688PWR operates across -40°C ~ 85°C with 36ns propagation delay. Select based on thermal and timing requirements of your application.

Q: Are the discontinued parts (CD74HC688PWT and SN74HC688PWT) still usable?

A: Yes. Discontinued status at DiGi Electronics does not affect functional performance. These parts remain electrically and mechanically equivalent to active variants. Availability through alternative distributors may be limited; verify stock before design commitment.

Q: Does the 36ns propagation delay of SN74HC688PWR affect circuit timing?

A: The 7ns difference from the original 29ns specification must be evaluated against your system timing budget. For most logic-level comparison applications, this margin is acceptable. Perform timing analysis if your design operates near propagation delay limits.

Q: What packaging format should I specify for production?

A: CD74HC688PWR is supplied in Tape & Reel (TR) format, suitable for automated assembly. SN74HC688PWR is supplied in Cut Tape (CT) & Digi-Reel format. Confirm packaging availability with your distributor and verify compatibility with your assembly equipment.

Q: Are all substitutes ROHS3 compliant?

A: Yes. All listed substitutes maintain ROHS3 compliance and REACH unaffected status, meeting current environmental regulations.