FST3257MTCX Equivalent & Substitute Parts

Part Overview

The FST3257MTCX is a 4 x 2:1 Multiplexer/Demultiplexer logic IC manufactured by onsemi in a 16-TSSOP surface mount package. This component is classified as Obsolete, with 55,200 units currently in stock. The part operates across a single supply voltage range of 3V to 5.5V and supports operating temperatures from -40°C to 85°C. Due to its obsolete status, identifying equivalent and substitute parts is necessary for design continuity, long-term availability assurance, and supply chain planning.

Substiute Parts

FST3257MTCX

onsemiIn Stock: 55297FST3257MTCX Datasheet

Current PartRFQ

74FST3257DTR2G

onsemiIn Stock: 330374FST3257DTR2G Datasheet

DirectRFQ

74CBTLV3257PW,118

NXP SemiconductorsIn Stock: 609674CBTLV3257PW,118 Datasheet

DirectRFQ

SN74CBT3257CPWR

Texas InstrumentsIn Stock: 47791SN74CBT3257CPWR Datasheet

DirectRFQ

SN74CBT3257PW

Texas InstrumentsIn Stock: 2324SN74CBT3257PW Datasheet

DirectRFQ

SN74CBT3257PWR

Texas InstrumentsIn Stock: 2476SN74CBT3257PWR Datasheet

DirectRFQ

CBT3257ADS,118

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

SimilarRFQ

CBT3257APW,118

Nexperia USA Inc.In Stock: 3196CBT3257APW,118 Datasheet

SimilarRFQ

PI5C3257LE

Diodes IncorporatedIn Stock: 1443PI5C3257LE Datasheet

SimilarRFQ

PI5C3257LEX

Diodes IncorporatedIn Stock: 15451PI5C3257LEX Datasheet

SimilarRFQ

SN74CBT3257CDBR

Texas InstrumentsIn Stock: 2127SN74CBT3257CDBR Datasheet

SimilarRFQ

SN74CBT3257CPW

Texas InstrumentsIn Stock: 2206SN74CBT3257CPW Datasheet

SimilarRFQ

SN74CBT3257DBR

Texas InstrumentsIn Stock: 4574SN74CBT3257DBR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the FST3257MTCX is determined by the following critical parameters:

Primary Substitution Criteria:

• Circuit configuration: 4 x 2:1 multiplexer/demultiplexer topology
• Package type: 16-TSSOP surface mount (0.173", 4.40mm width)
• Voltage supply compatibility: Overlapping or compatible supply voltage ranges
• Operating temperature range: Minimum -40°C to 85°C support
• Independent circuits: Single circuit configuration

Substitution Categories:

Direct Substitutes (Identical Circuit & Package): Parts with 4 x 2:1 configuration in 16-TSSOP package and compatible voltage/temperature specifications.

Similar Substitutes (Different Package): Parts with 4 x 2:1 configuration in alternative SSOP packages (16-SSOP, 0.154" or 0.209" width) with compatible electrical specifications. Package differences require PCB layout modification.

Limited Substitutes (Different Circuit Configuration): The 74CBTLV3257PW,118 features a 4 x 1:2 configuration with 4 independent circuits, differing from the 4 x 2:1 single-circuit topology. This part operates at lower voltage (2.3V ~ 3.6V) and higher temperature range (-40°C ~ 125°C) but requires functional verification due to circuit topology differences.

Parameter Comparison

Engineering Selection Recommendations

Preferred Direct Substitutes (Active Status):

SN74CBT3257CPWR and CBT3257APW,118 are the primary recommendations. Both maintain the 4 x 2:1 circuit configuration in 16-TSSOP packages with Active product status, ensuring long-term availability and manufacturer support. SN74CBT3257CPWR is available in Cut Tape & Digi-Reel® packaging, matching the original FST3257MTCX format. CBT3257APW,118 is available in Tape & Reel format. Both are ROHS3 compliant with MSL 1 rating.

Secondary Direct Substitutes (Last Time Buy Status):

74FST3257DTR2G, SN74CBT3257PW, SN74CBT3257PWR, PI5C3257LE, and PI5C3257LEX maintain 4 x 2:1 configuration and 16-TSSOP packaging but carry Last Time Buy status. These parts have limited remaining inventory and no future production. Selection should be based on immediate project requirements and supply chain planning.

Package Variant Substitutes:

CBT3257ADS,118 and SN74CBT3257CDBR provide 4 x 2:1 functionality in 16-SSOP packages (0.154" and 0.209" widths respectively). These require PCB layout modification due to different pin spacing but maintain electrical compatibility and Active product status.

Voltage-Constrained Substitutes:

PI5C3257LE and PI5C3257LEX operate within a narrower voltage range (4.75V ~ 5.25V) compared to the FST3257MTCX (3V ~ 5.5V). These parts are suitable only for applications with stable 5V supply rails.

Topology-Different Substitute:

74CBTLV3257PW,118 features a different circuit topology (4 x 1:2 with 4 independent circuits versus 4 x 2:1 with 1 circuit) and operates at lower voltage (2.3V ~ 3.6V). This part is not a direct functional equivalent and requires complete functional verification before implementation.

Frequently Asked Questions (FAQ)

Q: Can I use SN74CBT3257CPWR as a direct replacement for FST3257MTCX?

A: SN74CBT3257CPWR is functionally compatible as a direct substitute. Both parts feature 4 x 2:1 multiplexer/demultiplexer configuration in 16-TSSOP packages. The voltage supply range for SN74CBT3257CPWR (4.5V ~ 5.5V) is a subset of FST3257MTCX (3V ~ 5.5V), so applications operating above 4.5V are fully compatible. Applications requiring operation below 4.5V require alternative parts.

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

A: Both are surface mount packages with 16 pins, but differ in physical dimensions. 16-TSSOP has a width of 0.173" (4.40mm), while 16-SSOP variants range from 0.154" (3.90mm) to 0.209" (5.30mm). These dimensional differences require different PCB footprints and cannot be used interchangeably without layout modification.

Q: Why does 74CBTLV3257PW,118 have a different circuit configuration?

A: The 74CBTLV3257PW,118 is a 4 x 1:2 multiplexer with 4 independent circuits, fundamentally different from the 4 x 2:1 single-circuit topology of FST3257MTCX. The circuit topology determines signal routing and control logic. This part is not a functional equivalent and requires complete application redesign.

Q: Which substitute has the longest product life?

A: SN74CBT3257CPWR, CBT3257APW,118, CBT3257ADS,118, and SN74CBT3257CDBR all carry Active product status, indicating ongoing manufacturer support and production. All other substitutes are classified as Last Time Buy or Obsolete.

Q: Can I use PI5C3257LE in a 3V application?

A: No. PI5C3257LE operates within a voltage range of 4.75V ~ 5.25V and is not specified for 3V operation. Applications requiring 3V operation must use parts with lower voltage specifications, such as 74CBTLV3257PW,118 (2.3V ~ 3.6V).

Q: What is the difference between Cut Tape and Tape & Reel packaging?

A: Cut Tape (CT) & Digi-Reel® packaging provides individual component strips suitable for manual handling and smaller quantity orders. Tape & Reel (TR) packaging provides continuous reels for automated assembly equipment. Both formats contain the same component; packaging selection depends on assembly process requirements.