FST3345QSC Equivalent & Substitute Parts

Part Overview

The FST3345QSC is an 8 x 1:1 bus switch logic IC manufactured by onsemi in a 20-QSOP surface mount package. This component operates with a single supply voltage between 4V and 5.5V and supports operating temperatures from -40°C to 85°C. The FST3345QSC is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements.

Substiute Parts

FST3345QSC

onsemiIn Stock: 678FST3345QSC Datasheet

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SN74CBT3345CDBQR

Texas InstrumentsIn Stock: 813SN74CBT3345CDBQR Datasheet

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SN74CBT3345CPW

Texas InstrumentsIn Stock: 1608SN74CBT3345CPW Datasheet

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SN74CBT3345CPWR

Texas InstrumentsIn Stock: 3736SN74CBT3345CPWR Datasheet

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SN74CBT3345DGVR

Texas InstrumentsIn Stock: 4860SN74CBT3345DGVR Datasheet

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SN74CBT3345PW

Texas InstrumentsIn Stock: 1993SN74CBT3345PW Datasheet

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SN74CBT3345PWR

Texas InstrumentsIn Stock: 2320SN74CBT3345PWR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the FST3345QSC is determined by the following critical parameters:

• Circuit Configuration: All substitutes must maintain 8 x 1:1 bus switch topology with 1 independent circuit
• Voltage Supply: Operating range must encompass or match 4V ~ 5.5V single supply requirement
• Operating Temperature: Must support -40°C ~ 85°C range
• Mounting Type: Surface mount only
• Package Compatibility: Physical dimensions and pin count must be compatible with PCB layout

The Texas Instruments SN74CBT3345 series parts meet these core functional requirements. Substitutes are available in multiple package variants (20-SSOP, 20-TSSOP, 20-TVSOP) and packaging formats (Tube, Tape & Reel). All substitute parts operate within the required voltage and temperature specifications.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: SN74CBT3345CPWR

The SN74CBT3345CPWR is the preferred substitute for the FST3345QSC. This part maintains full functional equivalence with identical circuit configuration, voltage supply range (4.5V ~ 5.5V), and operating temperature specifications. The SN74CBT3345CPWR carries Active product status with ROHS3 compliance and unlimited moisture sensitivity rating. Tape & Reel packaging supports high-volume production requirements.

Secondary Recommendation: SN74CBT3345CPW

The SN74CBT3345CPW provides functional equivalence with Active product status and ROHS3 compliance. This variant is supplied in Tube packaging and maintains identical electrical specifications. The higher inventory level (1558 units) supports immediate availability for prototyping and low-to-medium volume applications.

Package Consideration: SN74CBT3345CDBQR

The SN74CBT3345CDBQR maintains the closest physical package footprint to the original FST3345QSC, both using 20-pin packages with 0.154" width. This variant is Active status with ROHS3 compliance. However, the 4.5V minimum supply voltage (versus 4V for the original) requires verification against circuit design specifications.

End-of-Life Alternatives: SN74CBT3345DGVR, SN74CBT3345PW, SN74CBT3345PWR

These parts carry Last Time Buy status and should be selected only when specific package requirements or existing inventory constraints necessitate their use. All maintain functional equivalence and ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can SN74CBT3345 series parts directly replace the FST3345QSC?

A: Yes, all listed SN74CBT3345 variants provide functional equivalence. The 8 x 1:1 bus switch topology, single supply operation, and temperature range are identical. Voltage supply range differs slightly (4.5V ~ 5.5V versus 4V ~ 5.5V), requiring verification that your circuit operates above 4.5V minimum.

Q: What is the difference between the various SN74CBT3345 package options?

A: Package differences are physical only. 20-SSOP (0.154" width) most closely matches the original FST3345QSC footprint. 20-TSSOP and 20-TFSOP variants (0.173" width) are slightly wider but functionally identical. Package selection depends on PCB layout compatibility.

Q: Why do some substitutes show Last Time Buy status?

A: Last Time Buy status indicates Texas Instruments has announced end-of-life for these specific variants. SN74CBT3345CPWR and SN74CBT3345CPW maintain Active status and are recommended for new designs requiring long-term availability.

Q: Are all substitutes ROHS3 compliant?

A: Yes, all Texas Instruments SN74CBT3345 variants listed are ROHS3 compliant. The original FST3345QSC compliance status was not specified in available documentation.

Q: What is the significance of Moisture Sensitivity Level differences?

A: The FST3345QSC and most SN74CBT3345 variants carry MSL 1 (Unlimited), indicating no moisture sensitivity restrictions. The SN74CBT3345CDBQR carries MSL 2 (1 Year), requiring controlled storage conditions and bake-out procedures before reflow soldering if shelf life exceeds one year.

Q: Which substitute offers the best inventory availability?

A: The SN74CBT3345DGVR currently shows the highest inventory level at 4846 units. However, this part carries Last Time Buy status. For long-term availability, SN74CBT3345CPWR (3664 units, Active status) is the optimal choice.