FST34X245QSPX Equivalent & Substitute Parts

Part Overview

The FST34X245QSPX is an 8 x 1:1 bus switch logic IC manufactured by onsemi, housed in an 80-QVSOP surface mount package. This component functions as a multiplexer for digital signal routing in logic applications. The FST34X245QSPX is classified as obsolete, making identification of compatible substitute parts essential for ongoing design support and procurement continuity.

Substiute Parts

FST34X245QSPX

onsemiIn Stock: 2755FST34X245QSPX Datasheet

Current PartRFQ

SN74CBT34X245DBBR

Texas InstrumentsIn Stock: 3381SN74CBT34X245DBBR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the FST34X245QSPX is determined by the following critical parameters:

• Circuit Configuration: 8 x 1:1 bus switch topology
• Independent Circuits: 4 independent switching channels
• Voltage Supply Range: 4V ~ 5.5V single supply operation
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface mount technology
• Package Type: 80-pin FSOP/TFSOP variants
• Moisture Sensitivity: MSL 1 (Unlimited)

The SN74CBT34X245DBBR from Texas Instruments meets all substitution criteria. Both parts share identical circuit topology, voltage specifications, temperature range, and moisture sensitivity classification. The primary difference is the package variant (80-QVSOP versus 80-TSSOP) and active product status of the substitute.

Parameter Comparison

Engineering Selection Recommendations

The SN74CBT34X245DBBR is a direct functional substitute for the FST34X245QSPX. Selection of this substitute is supported by:

• Active Product Status: The SN74CBT34X245DBBR maintains active manufacturing status, ensuring long-term availability and supply chain stability compared to the obsolete FST34X245QSPX.
• Compliance Certification: The substitute carries ROHS3 compliance, meeting current environmental and regulatory standards.
• Electrical Compatibility: Both parts operate within overlapping voltage supply ranges (4.5V ~ 5.5V common window) and identical temperature specifications.
• Functional Equivalence: Identical 8 x 1:1 circuit topology with 4 independent circuits ensures pin-compatible operation in existing designs.
• Packaging Consideration: The 80-TSSOP package is wider (6.10mm) than the 80-QVSOP (3.90mm). PCB layout verification is required to confirm physical fit within existing footprints.

Frequently Asked Questions (FAQ)

Q: Can the SN74CBT34X245DBBR replace the FST34X245QSPX directly?

A: Functionally yes, with one critical consideration. Both parts share identical circuit topology, voltage specifications, and temperature range. However, the package footprint differs: 80-TSSOP (6.10mm width) versus 80-QVSOP (3.90mm width). PCB layout must accommodate the wider package, or a new footprint design is required.

Q: What is the voltage supply difference between these parts?

A: The FST34X245QSPX operates at 4V ~ 5.5V, while the SN74CBT34X245DBBR operates at 4.5V ~ 5.5V. The substitute has a narrower lower voltage limit. Designs operating below 4.5V require verification that system voltage remains within the substitute's specification.

Q: Why is the FST34X245QSPX obsolete?

A: Product obsolescence is determined by the manufacturer. The onsemi FST34X245QSPX has reached end-of-life status. The Texas Instruments SN74CBT34X245DBBR remains in active production, providing continuity for new designs and ongoing support.

Q: Are there any compliance differences?

A: The SN74CBT34X245DBBR carries ROHS3 compliance certification. The FST34X245QSPX compliance status is not specified in available documentation. Both parts share identical moisture sensitivity classification (MSL 1, Unlimited).

Q: What is the pin count and package type?

A: Both parts are 80-pin devices. The FST34X245QSPX uses 80-QVSOP packaging, while the SN74CBT34X245DBBR uses 80-TSSOP packaging. Pin assignments are identical; physical package dimensions differ.