74FST3251QSR Equivalent & Substitute Parts

Part Overview

The 74FST3251QSR is a Multiplexer/Demultiplexer logic IC with a 1 x 8:1 circuit configuration, manufactured by onsemi in a 16-QSOP surface mount package. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The part operates across a single supply voltage range of 4V to 5.5V with an operating temperature range of -40°C to 85°C.

Substiute Parts

74FST3251QSR

onsemiIn Stock: 147474FST3251QSR Datasheet

Current PartRFQ

SN74CBT3251DBQR

Texas InstrumentsIn Stock: 3742SN74CBT3251DBQR Datasheet

DirectRFQ

PI5C3251QE

Diodes IncorporatedIn Stock: 1470PI5C3251QE Datasheet

SimilarRFQ

QS3251QG

Renesas Electronics CorporationIn Stock: 1238QS3251QG Datasheet

SimilarRFQ

QS3251QG8

Renesas Electronics CorporationIn Stock: 1625QS3251QG8 Datasheet

SimilarRFQ

SN74CBT3251DBR

Texas InstrumentsIn Stock: 5598SN74CBT3251DBR Datasheet

SimilarRFQ

PI5C3251QEX

Diodes IncorporatedIn Stock: 26909PI5C3251QEX Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 74FST3251QSR is determined by the following critical parameters:

• Circuit configuration: 1 x 8:1 multiplexer/demultiplexer topology
• Supply voltage compatibility: Minimum 4V to maximum 5.5V overlap
• Operating temperature range: -40°C to 85°C
• Package type: 16-SSOP surface mount with 0.154" (3.90mm) width
• Single independent circuit requirement

Substitute parts are grouped into two categories:

Direct Substitutes: Parts with identical or overlapping electrical specifications and compatible package dimensions (SN74CBT3251DBQR, PI5C3251QE, QS3251QG, QS3251QG8, SN74CBT3251DBR).

Parametric Equivalents: Parts meeting all functional and electrical requirements with full parameter compatibility (PI5C3251QEX).

Parameter Comparison

Engineering Selection Recommendations

For RoHS3 Compliance Requirements: All substitute parts except the original 74FST3251QSR meet ROHS3 compliance standards. QS3251QG8 (Renesas Electronics) is the only part with Active product status, making it the preferred choice for new designs requiring long-term availability and regulatory compliance.

For Voltage Supply Compatibility: PI5C3251QE and PI5C3251QEX (Diodes Incorporated) maintain the full 4V to 5.5V supply range of the original part. SN74CBT3251DBQR, SN74CBT3251DBR, QS3251QG, and QS3251QG8 operate within narrower ranges (4.5V to 5.5V or 4.75V to 5.25V), requiring verification of system supply voltage specifications.

For Moisture Sensitivity: PI5C3251QE, QS3251QG, QS3251QG8, SN74CBT3251DBR, and PI5C3251QEX all feature MSL 1 (Unlimited), matching the original part's moisture handling capability. SN74CBT3251DBQR has MSL 2 (1 Year), requiring controlled storage conditions.

For Package Dimensions: SN74CBT3251DBR features a 16-SSOP package with 0.209" (5.30mm) width, differing from the standard 0.154" (3.90mm) width. All other substitutes maintain the original package width specification.

Frequently Asked Questions (FAQ)

Q: Can I use QS3251QG8 as a direct replacement for 74FST3251QSR? A: QS3251QG8 is functionally equivalent with identical circuit configuration, operating temperature range, and package dimensions. However, its supply voltage range (4.75V to 5.25V) is narrower than the original (4V to 5.5V). Substitution is valid only if your system supply voltage falls within the 4.75V to 5.25V window.

Q: What is the difference between PI5C3251QE and PI5C3251QEX? A: Both parts are manufactured by Diodes Incorporated with identical electrical specifications and supply voltage range (4V to 5.5V). The primary difference is packaging: PI5C3251QE is supplied in Tube format, while PI5C3251QEX is supplied in Tape & Reel (TR) format. PI5C3251QEX offers higher inventory availability (26,800 pcs vs. 1,430 pcs).

Q: Why does SN74CBT3251DBR have a different package width? A: SN74CBT3251DBR uses a 16-SSOP package with 0.209" (5.30mm) width, compared to the standard 0.154" (3.90mm) width of other substitutes. This dimension difference may affect PCB layout compatibility. Verify footprint compatibility before selection.

Q: Which substitute part has the longest product lifecycle? A: QS3251QG8 (Renesas Electronics) is the only part with Active product status, indicating ongoing production and availability. All other substitutes are classified as Last Time Buy, indicating limited future availability.

Q: Are all substitutes RoHS3 compliant? A: All substitute parts listed are ROHS3 compliant. The original 74FST3251QSR is RoHS non-compliant. If RoHS compliance is required, any of the listed substitutes is acceptable.