74FST3244QSR Equivalent & Substitute Parts

Part Overview

The 74FST3244QSR is a Bus Switch 4 x 1:1 logic IC manufactured by onsemi in a 20-QSOP package. This component functions as a high-speed bus switch for multiplexing and signal routing applications. The part is currently obsolete, making equivalent substitutes necessary for new designs or component replenishment. Substitute parts must maintain identical electrical specifications and compatible packaging to ensure direct replacement capability.

Substiute Parts

74FST3244QSR

onsemiIn Stock: 102674FST3244QSR Datasheet

Current PartRFQ

SN74CBT3244CDGVR

Texas InstrumentsIn Stock: 2842SN74CBT3244CDGVR Datasheet

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SN74CBT3244CPW

Texas InstrumentsIn Stock: 1416SN74CBT3244CPW Datasheet

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SN74CBT3244CPWR

Texas InstrumentsIn Stock: 2244SN74CBT3244CPWR Datasheet

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SN74CBT3244DBQR

Texas InstrumentsIn Stock: 3335SN74CBT3244DBQR Datasheet

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SN74CBT3244DBR

Texas InstrumentsIn Stock: 2437SN74CBT3244DBR Datasheet

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SN74CBT3244DGVR

Texas InstrumentsIn Stock: 4992SN74CBT3244DGVR Datasheet

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SN74CBT3244PW

Texas InstrumentsIn Stock: 2164SN74CBT3244PW Datasheet

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SN74CBT3244PWR

Texas InstrumentsIn Stock: 22454SN74CBT3244PWR Datasheet

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SN74CBT3244CDBQR

Texas InstrumentsIn Stock: 3471SN74CBT3244CDBQR Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following criteria:

Primary Substitution Criteria:

• Circuit configuration: 4 x 1:1 topology
• Independent circuits: 2
• Voltage supply range: 4V ~ 5.5V minimum compatibility
• Operating temperature: -40°C ~ 85°C
• Mounting type: Surface Mount
• Package compatibility: 20-SSOP or equivalent SSOP variants

Grouping Logic: Substitute parts are grouped by package type and product status. The 74FST3244QSR (20-QSOP) can be replaced by Texas Instruments SN74CBT3244 series parts in 20-SSOP packages with matching electrical specifications. Parts with identical voltage supply ranges (4V ~ 5.5V) and temperature ratings provide direct electrical compatibility. Parts with expanded voltage ranges (4.5V ~ 5.5V) are functionally compatible but represent a narrower operating window.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: SN74CBT3244CDBQR

This part provides the closest electrical and mechanical match to the 74FST3244QSR. It maintains the identical voltage supply range (4V ~ 5.5V), temperature rating (-40°C ~ 85°C), and 20-SSOP package footprint (0.154", 3.90mm width). The part is currently in Active status with ROHS3 compliance, ensuring long-term availability and regulatory alignment.

Secondary Recommendation: SN74CBT3244CDGVR

This part matches the full voltage supply specification (4V ~ 5.5V) and temperature range. It uses a 20-TFSOP package (0.173", 4.40mm width), which requires PCB layout modification but maintains electrical compatibility. Active product status ensures continued supply.

Alternative Consideration: SN74CBT3244CPW

This part provides voltage supply compatibility (4V ~ 5.5V) and Active product status. The 20-TSSOP package (0.173", 4.40mm width) differs from the original, requiring PCB redesign.

Parts to Avoid for New Designs:

Parts with Last Time Buy or Obsolete status (SN74CBT3244DBQR, SN74CBT3244DBR, SN74CBT3244DGVR, SN74CBT3244PW, SN74CBT3244CPWR, SN74CBT3244PWR) should not be selected for new production designs due to limited future availability. These parts may be suitable only for legacy system maintenance where existing inventory exists.

Frequently Asked Questions (FAQ)

Q: Can SN74CBT3244CDBQR directly replace 74FST3244QSR without PCB modification?

A: Yes. Both parts use the 20-SSOP package with identical footprint dimensions (0.154", 3.90mm width). Electrical specifications match across voltage supply (4V ~ 5.5V) and temperature range (-40°C ~ 85°C). No PCB layout changes are required.

Q: What is the difference between 20-SSOP, 20-TSSOP, and 20-TFSOP packages?

A: These are all 20-pin small-outline packages with different body widths. The 20-SSOP (0.154" width) matches the original 74FST3244QSR footprint. The 20-TSSOP and 20-TFSOP (both 0.173" width) require PCB redesign. Pin pitch and lead spacing differ, making them incompatible without layout modification.

Q: Why do some substitutes specify 4.5V ~ 5.5V instead of 4V ~ 5.5V?

A: The narrower voltage range (4.5V ~ 5.5V) represents a tighter specification window. Parts with this range are electrically compatible in applications using 4.5V to 5.5V supply, but cannot guarantee operation at 4V. For designs requiring 4V operation, select parts with 4V ~ 5.5V specification.

Q: What does RoHS3 compliance mean for this component?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, and other hazardous materials. The original 74FST3244QSR is RoHS non-compliant. All Texas Instruments substitutes are ROHS3 compliant, meeting modern environmental and regulatory standards.

Q: Should I use parts with Last Time Buy status?

A: Last Time Buy status indicates the manufacturer will discontinue production. These parts should not be selected for new designs requiring long-term component availability. Use only for legacy system maintenance where existing inventory is available.

Q: Are there any functional differences between the onsemi 74FST3244QSR and Texas Instruments SN74CBT3244 series?

A: Both implement identical 4 x 1:1 bus switch functionality with 2 independent circuits. Electrical performance, switching characteristics, and logic levels are equivalent across the specified voltage and temperature ranges. The primary differences are manufacturer, package variant, and product lifecycle status.