74FST3125QSR Bus Switch Equivalent & Substitute Parts

Part Overview

The 74FST3125QSR is a 1 x 1:1 bus switch logic IC manufactured by onsemi in a 16-QSOP surface mount package. This component features 4 independent circuits and operates across a 4V to 5.5V single supply voltage range with an operating temperature range of -40°C to 85°C. The part is currently classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity.

Substiute Parts

74FST3125QSR

onsemiIn Stock: 94874FST3125QSR Datasheet

Current PartRFQ

SN74CBT3125DBQR

Texas InstrumentsIn Stock: 3870SN74CBT3125DBQR Datasheet

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PI5C3125QE

Diodes IncorporatedIn Stock: 7405PI5C3125QE Datasheet

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PI5C3125QEX

Diodes IncorporatedIn Stock: 17979PI5C3125QEX Datasheet

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QS3125QG

Renesas Electronics CorporationIn Stock: 1392QS3125QG Datasheet

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QS3125QG8

Renesas Electronics CorporationIn Stock: 19276QS3125QG8 Datasheet

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SN74CBT3125CDBQR

Texas InstrumentsIn Stock: 806SN74CBT3125CDBQR Datasheet

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SN74CBT3125CDBR

Texas InstrumentsIn Stock: 29146SN74CBT3125CDBR Datasheet

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SN74CBT3125CPW

Texas InstrumentsIn Stock: 924SN74CBT3125CPW Datasheet

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SN74CBT3125CPWR

Texas InstrumentsIn Stock: 2487SN74CBT3125CPWR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 74FST3125QSR is determined by the following critical parameters:

• Circuit Configuration: 1 x 1:1 topology with 4 independent circuits
• Package Type: 16-pin SSOP/QSOP surface mount package (0.154", 3.90mm width)
• Voltage Supply Range: Single supply operation between 4V and 5.5V
• Operating Temperature Range: -40°C to 85°C
• Mounting Type: Surface mount technology

Parts meeting these electrical and mechanical specifications are functionally equivalent and can replace the 74FST3125QSR in circuit applications. Substitute parts are grouped by manufacturer and product status, with variations in packaging format (Tube vs. Tape & Reel) and compliance certifications noted.

Parameter Comparison

Engineering Selection Recommendations

Direct Substitutes (16-pin QSOP/SSOP Package)

PI5C3125QE and PI5C3125QEX from Diodes Incorporated maintain the original 16-QSOP package footprint and offer ROHS3 compliance with unlimited moisture sensitivity rating. Both parts are in Last Time Buy status with substantial inventory availability (7,300 and 17,920 units respectively).

QS3125QG and QS3125QG8 from Renesas Electronics Corporation provide active product status with ROHS3 compliance and unlimited MSL rating. These parts operate within a narrower voltage supply window (4.75V ~ 5.25V) compared to the original 4V ~ 5.5V specification. QS3125QG8 offers higher inventory levels (19,208 units).

SN74CBT3125DBQR and SN74CBT3125CDBQR from Texas Instruments are ROHS3 compliant alternatives in 16-SSOP package configuration. SN74CBT3125CDBQR maintains active product status with 765 units in stock, while SN74CBT3125DBQR is Last Time Buy with 3,770 units available.

Alternative Packages (14-pin SSOP/TSSOP)

SN74CBT3125CDBR, SN74CBT3125CPW, and SN74CBT3125CPWR from Texas Instruments provide active product status and ROHS3 compliance in 14-pin package variants (14-SSOP and 14-TSSOP). These alternatives require PCB layout modification due to different pin counts and package dimensions.

Frequently Asked Questions (FAQ)

Q: Can I use a 14-pin package substitute in place of the 16-pin 74FST3125QSR?

A: No. The 14-pin variants (SN74CBT3125CDBR, SN74CBT3125CPW, SN74CBT3125CPWR) have different pin configurations and package footprints. These require PCB redesign and are not direct drop-in replacements.

Q: What is the difference between PI5C3125QE and PI5C3125QEX?

A: Both parts are functionally identical with the same electrical specifications and 16-QSOP package. The primary difference is packaging format: PI5C3125QE is supplied in Tube, while PI5C3125QEX is supplied in Tape & Reel (TR). PI5C3125QEX has higher inventory availability (17,920 units vs. 7,300 units).

Q: Are Renesas QS3125QG and QS3125QG8 interchangeable?

A: Yes. Both parts share identical electrical specifications and 16-QSOP package configuration. The primary difference is packaging format and inventory levels. QS3125QG8 offers significantly higher stock (19,208 units vs. 1,338 units).

Q: Does the narrower voltage range of Renesas parts (4.75V ~ 5.25V) affect compatibility?

A: The Renesas voltage specification is narrower than the original 74FST3125QSR (4V ~ 5.5V) and the Texas Instruments alternatives (4.5V ~ 5.5V). Verify your circuit's actual supply voltage operates within the 4.75V ~ 5.25V window before selecting Renesas parts.

Q: What is the significance of RoHS compliance status?

A: The original 74FST3125QSR is RoHS non-compliant. All substitute parts listed are ROHS3 compliant, meeting current environmental and regulatory requirements for new designs and production.

Q: How does Moisture Sensitivity Level (MSL) impact component handling?

A: MSL 1 (Unlimited) parts like PI5C3125QE, PI5C3125QEX, QS3125QG, QS3125QG8, and most Texas Instruments variants have no moisture exposure time restrictions. MSL 2 (1 Year) parts like SN74CBT3125DBQR and SN74CBT3125CDBQR require storage in dry conditions and have a one-year floor life limit after moisture exposure.