74FST3257QSR Equivalent & Substitute Parts

Part Overview

The 74FST3257QSR is a Multiplexer/Demultiplexer logic IC with 4 x 2:1 circuit configuration, manufactured by onsemi in a 16-QSOP surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The 74FST3257QSR operates with single supply voltage between 4V and 5.5V across an operating temperature range of -40°C to 85°C. Substitute parts must maintain functional equivalence through matching circuit topology, electrical parameters, and mechanical compatibility.

Substiute Parts

74FST3257QSR

onsemiIn Stock: 111674FST3257QSR Datasheet

Current PartRFQ

SN74CBT3257CDBQR

Texas InstrumentsIn Stock: 2499SN74CBT3257CDBQR Datasheet

DirectRFQ

SN74CBT3257DBQR

Texas InstrumentsIn Stock: 3548SN74CBT3257DBQR Datasheet

DirectRFQ

CBT3257ADS,118

Nexperia USA Inc.In Stock: 1917CBT3257ADS,118 Datasheet

SimilarRFQ

PI5C3257QE

Diodes IncorporatedIn Stock: 10203PI5C3257QE Datasheet

SimilarRFQ

QS3257QG

Renesas Electronics CorporationIn Stock: 5851QS3257QG Datasheet

SimilarRFQ

SN74CBT3257CDBR

Texas InstrumentsIn Stock: 2127SN74CBT3257CDBR Datasheet

SimilarRFQ

SN74CBT3257DBR

Texas InstrumentsIn Stock: 4574SN74CBT3257DBR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 74FST3257QSR is determined by the following critical parameters:

• Circuit Topology: All substitutes must maintain 4 x 2:1 multiplexer/demultiplexer configuration with 1 independent circuit
• Voltage Supply: Single supply operation within compatible voltage ranges (4V ~ 5.5V or 4.5V ~ 5.5V or 4.75V ~ 5.25V)
• Operating Temperature: -40°C to 85°C range
• Package Type: 16-SSOP or 16-QSOP surface mount packages with 0.154" or 0.209" width variants
• Mounting: Surface mount technology

Substitute parts are categorized as direct or similar based on product status and compliance certifications. Direct substitutes (SN74CBT3257CDBQR, SN74CBT3257DBQR) are active or last-time-buy products from established manufacturers. Similar substitutes (CBT3257ADS,118, PI5C3257QE, QS3257QG, SN74CBT3257CDBR, SN74CBT3257DBR) are active products that meet all functional and electrical requirements.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Active Status)

SN74CBT3257CDBQR (Texas Instruments) and CBT3257ADS,118 (Nexperia USA Inc.) are recommended as primary substitutes. Both are active products with ROHS3 compliance and maintain the 4 x 2:1 circuit configuration with compatible voltage and temperature specifications. SN74CBT3257CDBQR offers tape and reel packaging with 2-year MSL rating, while CBT3257ADS,118 provides unlimited MSL with tape and reel delivery.

Secondary Substitutes (Active Status)

PI5C3257QE (Diodes Incorporated) and QS3257QG (Renesas Electronics Corporation) are active alternatives with ROHS3 compliance. Both maintain the 16-QSOP package format matching the original 74FST3257QSR and offer unlimited MSL. Voltage supply range is narrower (4.75V ~ 5.25V) compared to the original specification.

Last-Time-Buy Alternatives

SN74CBT3257DBQR and SN74CBT3257DBR (Texas Instruments) are designated as last-time-buy products. These remain functionally equivalent but have limited procurement windows. SN74CBT3257CDBR and SN74CBT3257DBR feature a wider 16-SSOP package (0.209" width) and should be evaluated for PCB layout compatibility.

Compliance Consideration

The original 74FST3257QSR is RoHS non-compliant. All substitute parts listed are ROHS3 compliant, supporting modern manufacturing and environmental standards.

Frequently Asked Questions (FAQ)

Q: Can I directly replace 74FST3257QSR with any of these substitutes?

A: All listed substitutes maintain the 4 x 2:1 multiplexer/demultiplexer circuit topology and operate within compatible voltage and temperature ranges. However, verify package dimensions for PCB layout compatibility. The original uses 16-QSOP (0.154" width), while most substitutes use 16-SSOP with either 0.154" or 0.209" width variants.

Q: What is the difference between 16-QSOP and 16-SSOP packages?

A: Both are surface mount packages with 16 pins and similar footprints. QSOP and SSOP designations may vary by manufacturer but are mechanically compatible in most applications. Verify exact pin spacing and lead dimensions with datasheets before PCB layout finalization.

Q: Why do some substitutes have narrower voltage ranges?

A: PI5C3257QE and QS3257QG specify 4.75V ~ 5.25V supply voltage, which is narrower than the original 4V ~ 5.5V range. These parts remain functionally equivalent for standard 5V logic applications but may not operate at the lower voltage extreme (4V ~ 4.75V) if required by your design.

Q: Which substitute offers the best long-term availability?

A: SN74CBT3257CDBQR (Texas Instruments) and CBT3257ADS,118 (Nexperia USA Inc.) are designated as active products with no end-of-life announcements, providing the best long-term procurement stability.

Q: Are there packaging differences I should consider?

A: Yes. SN74CBT3257CDBR and SN74CBT3257DBR use 16-SSOP with 0.209" width, which is wider than the standard 0.154" width used by other substitutes. Confirm PCB footprint compatibility before selection.

Q: What does MSL (Moisture Sensitivity Level) mean for my procurement?

A: MSL indicates moisture sensitivity during storage and handling. MSL 1 (unlimited) parts like CBT3257ADS,118, PI5C3257QE, and QS3257QG have no moisture-related storage restrictions. MSL 2 (1 Year) parts like SN74CBT3257CDBQR require controlled storage conditions and must be used within one year of packaging.