FST3126QSC Equivalent & Substitute Parts

Part Overview

The FST3126QSC is a bus switch IC manufactured by onsemi, configured as a 1 x 1:1 logic switch with 4 independent circuits in a 16-QSOP surface mount package. This component operates across a single supply voltage range of 4V to 5.5V and supports operating temperatures from -40°C to 85°C. The FST3126QSC is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and procurement continuity.

Substiute Parts

FST3126QSC

onsemiIn Stock: 1096FST3126QSC Datasheet

Current PartRFQ

SN74CBT3126DBQR

Texas InstrumentsIn Stock: 5191SN74CBT3126DBQR Datasheet

DirectRFQ

PI5C3126QEX

Diodes IncorporatedIn Stock: 9361PI5C3126QEX Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the FST3126QSC are qualified based on the following electrical and mechanical parameters:

• Circuit Configuration: Must maintain 1 x 1:1 topology with 4 independent circuits
• Voltage Supply Range: Must support the 4V to 5.5V operating window
• Operating Temperature Range: Must cover -40°C to 85°C
• Package Compatibility: Must use equivalent 16-pin surface mount packages (16-QSOP or 16-SSOP with matching 0.154" width and 3.90mm dimensions)
• Functional Type: Must be a bus switch IC with identical switching characteristics

The following parts meet these substitution criteria:

1. SN74CBT3126DBQR (Texas Instruments) – Direct functional equivalent with compatible 16-SSOP packaging
2. PI5C3126QEX (Diodes Incorporated) – Direct functional equivalent with compatible 16-QSOP packaging

Parameter Comparison

Engineering Selection Recommendations

Both substitute parts provide functional equivalence to the FST3126QSC with the following considerations:

SN74CBT3126DBQR (Texas Instruments) – This part carries Last Time Buy status and is ROHS3 compliant. The voltage supply range is narrower (4.5V minimum versus 4V), which may require design review if the original application operates below 4.5V. Moisture sensitivity is rated at MSL 2 (1 Year), requiring controlled storage conditions.

PI5C3126QEX (Diodes Incorporated) – This part also carries Last Time Buy status and is ROHS3 compliant. The voltage supply range matches the substitute criteria (4.5V minimum). Moisture sensitivity is rated at MSL 1 (Unlimited), providing more flexible storage and handling conditions compared to the Texas Instruments alternative.

Both parts maintain identical circuit configuration, independent circuit count, operating temperature range, and package dimensions. Selection between these substitutes should be based on supply chain availability, voltage margin requirements, and moisture sensitivity handling capabilities.

Frequently Asked Questions (FAQ)

Q: Can the SN74CBT3126DBQR replace the FST3126QSC in all applications?

A: The SN74CBT3126DBQR is functionally equivalent across circuit configuration, independent circuits, operating temperature, and package dimensions. However, its minimum supply voltage is 4.5V versus the original 4V. Applications operating below 4.5V require design modification or selection of an alternative substitute.

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

A: Both packages are 16-pin surface mount configurations with identical pitch and body dimensions (0.154" width, 3.90mm). The primary difference is in lead geometry and manufacturing process. Both are mechanically and electrically compatible for this bus switch application.

Q: Why is the PI5C3126QEX rated MSL 1 while the SN74CBT3126DBQR is MSL 2?

A: Moisture Sensitivity Level (MSL) reflects the component's susceptibility to moisture absorption during storage. MSL 1 (Unlimited) allows indefinite shelf storage without special conditions. MSL 2 (1 Year) requires controlled humidity storage and has a one-year shelf life limit. Both ratings are acceptable; MSL 1 provides greater handling flexibility.

Q: Are both substitute parts ROHS3 compliant?

A: Yes, both SN74CBT3126DBQR and PI5C3126QEX are ROHS3 compliant. The original FST3126QSC does not specify RoHS status. Both substitutes meet current environmental compliance requirements.

Q: What is the inventory status of these substitute parts?

A: SN74CBT3126DBQR has 5,100 pieces available. PI5C3126QEX has 9,315 pieces available. Both are classified as Last Time Buy, indicating limited future availability.