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FST3244QSCX Equivalent & Substitute Parts
Part Overview
The FST3244QSCX is a bus switch logic IC manufactured by onsemi, featuring a 4 x 1:1 circuit configuration in a 20-QSOP package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The FST3244QSCX operates as a single-supply bus switch with voltage specifications of 4V to 5.5V and maintains an operating temperature range of -40°C to 85°C. Identifying compatible alternatives ensures design flexibility and supply chain resilience.
Substiute Parts
Key Parameters
| Parameter | FST3244QSCX |
|---|---|
| Manufacturer | onsemi |
| Type | Bus Switch |
| Circuit Configuration | 4 x 1:1 |
| Independent Circuits | 2 |
| Voltage Supply Source | Single Supply |
| Voltage - Supply Range | 4V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C |
| Mounting Type | Surface Mount |
| Package / Case | 20-LSSOP (0.154", 3.90mm Width) |
| Product Status | Obsolete |
| Moisture Sensitivity Level (MSL) | 1 (Unlimited) |
Substitute Part Grouping Explanation
Substitution of the FST3244QSCX is determined by strict equivalence in the following parameters:
- Circuit Type & Configuration: All substitutes must be 4 x 1:1 bus switches with 2 independent circuits
- Voltage Supply: Single supply operation within 4V to 5.5V range (or compatible subset)
- Operating Temperature: -40°C to 85°C range
- Mounting Type: Surface mount only
- Package Compatibility: Physical package dimensions must accommodate PCB layout constraints
The Texas Instruments 74CBT3244 series provides direct functional equivalents across multiple package options. Substitutes are grouped by package type: 20-SSOP, 20-TSSOP, and 20-TVSOP variants. All Texas Instruments alternatives maintain the core 4 x 1:1 bus switch functionality and voltage specifications required for direct replacement.
Parameter Comparison
| Part Number | Manufacturer | Circuit | Voltage Supply | Operating Temp | Package / Case | Product Status | RoHS Status | MSL |
|---|---|---|---|---|---|---|---|---|
| FST3244QSCX | onsemi | 4 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-LSSOP (0.154", 3.90mm) | Obsolete | Not specified | 1 (Unlimited) |
| SN74CBT3244CDBQR | Texas Instruments | 4 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP (0.154", 3.90mm) | Active | ROHS3 Compliant | 2 (1 Year) |
| SN74CBT3244CDGVR | Texas Instruments | 4 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TFSOP (0.173", 4.40mm) | Active | ROHS3 Compliant | 1 (Unlimited) |
| SN74CBT3244CPW | Texas Instruments | 4 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP (0.173", 4.40mm) | Active | ROHS3 Compliant | 1 (Unlimited) |
| SN74CBT3244CPWR | Texas Instruments | 4 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP (0.173", 4.40mm) | Active | ROHS3 Compliant | 1 (Unlimited) |
| SN74CBT3244DBQR | Texas Instruments | 4 x 1:1 | 4.5V ~ 5.5V | -40°C ~ 85°C | 20-SSOP (0.209", 5.30mm) | Last Time Buy | ROHS3 Compliant | 2 (1 Year) |
| SN74CBT3244DGVR | Texas Instruments | 4 x 1:1 | 4.5V ~ 5.5V | -40°C ~ 85°C | 20-TFSOP (0.173", 4.40mm) | Last Time Buy | ROHS3 Compliant | 1 (Unlimited) |
| SN74CBT3244PW | Texas Instruments | 4 x 1:1 | 4.5V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP (0.173", 4.40mm) | Last Time Buy | ROHS3 Compliant | 1 (Unlimited) |
| SN74CBT3244PWR | Texas Instruments | 4 x 1:1 | 4.5V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP (0.173", 4.40mm) | Obsolete | ROHS3 Compliant | 1 (Unlimited) |
Engineering Selection Recommendations
Primary Recommendation for New Designs: SN74CBT3244CDBQR or SN74CBT3244CPWR
The SN74CBT3244CDBQR and SN74CBT3244CPWR are the preferred substitutes for the FST3244QSCX. Both parts maintain active product status with Texas Instruments, ensuring long-term availability and supply chain stability. These alternatives are ROHS3 compliant and carry REACH unaffected certification, meeting modern environmental and regulatory requirements. The SN74CBT3244CDBQR operates within the full 4V to 5.5V supply range matching the original FST3244QSCX specification, while the SN74CBT3244CPWR provides equivalent functionality with MSL 1 moisture sensitivity rating.
Alternative Options: SN74CBT3244CDGVR and SN74CBT3244CPW
For designs where package footprint flexibility exists, the SN74CBT3244CDGVR (20-TFSOP) and SN74CBT3244CPW (20-TSSOP) offer active product status with identical electrical specifications. These variants provide design alternatives when PCB layout accommodates the slightly larger package dimensions (0.173" width versus 0.154" for SSOP variants).
Avoid for New Designs: SN74CBT3244DBQR, SN74CBT3244DGVR, SN74CBT3244PW, and SN74CBT3244PWR
These parts carry Last Time Buy or Obsolete status, indicating limited future availability. While functionally equivalent, they are not suitable for new production designs requiring long-term supply assurance.
Frequently Asked Questions (FAQ)
Q: Can SN74CBT3244CDBQR directly replace FST3244QSCX on existing PCBs?
A: Yes, with package verification. The SN74CBT3244CDBQR uses a 20-SSOP package with 0.154" width, matching the FST3244QSCX footprint. Verify PCB pad layout compatibility before assembly.
Q: What is the voltage supply difference between FST3244QSCX and some Texas Instruments substitutes?
A: The FST3244QSCX specifies 4V to 5.5V supply range. Some Texas Instruments alternatives (SN74CBT3244DBQR, DGVR, PW, PWR) specify 4.5V to 5.5V. For applications requiring 4V operation, use SN74CBT3244CDBQR or SN74CBT3244CPWR.
Q: Are all substitute parts ROHS3 compliant?
A: All Texas Instruments 74CBT3244 variants listed are ROHS3 compliant. The original FST3244QSCX RoHS status is not specified in available documentation.
Q: What packaging options are available for the 74CBT3244 series?
A: Three package variants are available: 20-SSOP (0.154" or 0.209" width), 20-TSSOP (0.173" width), and 20-TFSOP (0.173" width). Package selection depends on PCB layout constraints and manufacturing equipment capabilities.
Q: Which substitute has the best long-term availability?
A: SN74CBT3244CDBQR and SN74CBT3244CPWR maintain active product status with Texas Instruments, providing the highest assurance for long-term supply continuity and technical support.
Q: Is moisture sensitivity level (MSL) a critical factor for substitution?
A: MSL affects storage and handling requirements. The FST3244QSCX has MSL 1 (unlimited shelf life). Most active Texas Instruments alternatives also carry MSL 1, except SN74CBT3244CDBQR and SN74CBT3244DBQR which specify MSL 2 (1 year). MSL 2 parts require controlled storage conditions but are functionally equivalent.
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