FST3345QSCX Equivalent & Substitute Parts

Part Overview

The FST3345QSCX is an 8 x 1:1 bus switch logic IC manufactured by onsemi in a 20-QSOP surface mount package. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The FST3345QSCX operates with a single supply voltage between 4V and 5.5V across an operating temperature range of -40°C to 85°C, serving applications requiring multiplexed bus switching functionality.

Substiute Parts

FST3345QSCX

onsemiIn Stock: 7364FST3345QSCX 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 of the FST3345QSCX is determined by strict equivalence in the following parameters:

• Circuit Configuration: 8 x 1:1 bus switch topology
• Independent Circuits: 1 circuit per device
• Voltage Supply Source: Single supply operation
• Voltage Supply Range: Minimum 4.5V to 5.5V (note: FST3345QSCX supports 4V minimum; substitutes support 4.5V minimum)
• Operating Temperature Range: -40°C to 85°C
• Mounting Type: Surface mount
• Package Width: 3.90mm or 4.40mm (compatible with standard PCB layouts)

All identified substitute parts are manufactured by Texas Instruments under the 74CBT3345 base product number series. These parts maintain functional equivalence in bus switching capability and electrical specifications while offering different packaging options (20-SSOP, 20-TSSOP, 20-TVSOP) and availability statuses (Active or Last Time Buy).

Parameter Comparison

Engineering Selection Recommendations

For applications currently using the FST3345QSCX, the following selection criteria apply based on product status and compliance:

Primary Recommendation: SN74CBT3345CDBQR or SN74CBT3345CPWR. The SN74CBT3345CDBQR maintains active product status with ROHS3 compliance and 20-SSOP packaging (3.90mm width) matching the original footprint. The SN74CBT3345CPWR offers active status with ROHS3 compliance in 20-TSSOP packaging (4.40mm width) and unlimited MSL rating.

Secondary Options: SN74CBT3345CPW and SN74CBT3345PW provide ROHS3 compliance and unlimited MSL in 20-TSSOP packaging. Both are classified as Last Time Buy, indicating limited future availability.

Consideration for Extended Supply: SN74CBT3345DGVR is available in 20-TVSOP packaging with Last Time Buy status. This option provides the highest current inventory (4,846 pcs) among substitute parts.

All substitute parts maintain functional equivalence in bus switching topology, circuit configuration, and operating temperature range. The primary differentiation factor is packaging format and product lifecycle status. Designs requiring the exact 3.90mm package width should prioritize SN74CBT3345CDBQR. Designs with flexibility in package width can utilize the broader range of 4.40mm options with active product status.

Frequently Asked Questions (FAQ)

Q: Can the SN74CBT3345 series directly replace the FST3345QSCX without PCB modification?

A: Direct replacement depends on package selection. The SN74CBT3345CDBQR (20-SSOP, 3.90mm width) maintains the same footprint as the FST3345QSCX (20-LSSOP, 3.90mm width) and requires no PCB modification. The SN74CBT3345 variants in 20-TSSOP or 20-TVSOP packaging (4.40mm width) require PCB layout adjustment.

Q: What is the voltage supply difference between the FST3345QSCX and substitute parts?

A: The FST3345QSCX operates at 4V minimum supply voltage, while all Texas Instruments SN74CBT3345 substitutes operate at 4.5V minimum. Applications operating below 4.5V require design verification or alternative solutions.

Q: Which substitute part offers the best long-term availability?

A: The SN74CBT3345CDBQR and SN74CBT3345CPWR both carry Active product status, indicating ongoing manufacturing and availability. Parts designated Last Time Buy (SN74CBT3345DGVR, SN74CBT3345PW, SN74CBT3345PWR) have limited future availability and should be evaluated for long-term production requirements.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All identified SN74CBT3345 substitute parts are ROHS3 compliant. The original FST3345QSCX RoHS status is not specified in available documentation.

Q: What packaging options are available for the SN74CBT3345 series?

A: Three packaging formats are available: 20-SSOP (3.90mm width), 20-TSSOP (4.40mm width), and 20-TVSOP (4.40mm width). Package selection affects PCB footprint compatibility and MSL rating.

Q: Does MSL rating affect component selection?

A: MSL rating impacts moisture handling and storage requirements. The FST3345QSCX and most SN74CBT3345 variants carry MSL 1 (Unlimited), allowing indefinite storage without baking. The SN74CBT3345CDBQR carries MSL 2 (1 Year), requiring moisture control during storage and handling.