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74FST3245QSR Bus Switch 8 x 1:1 Equivalent & Substitute Parts
Part Overview
The 74FST3245QSR is an 8-channel 1:1 bus switch logic IC manufactured by onsemi in a 20-QSOP surface mount package. This component is classified as obsolete, indicating discontinued production and limited availability. The part operates with a single supply voltage range of 4V to 5.5V and supports operating temperatures from -40°C to 85°C. Due to its obsolete status and non-RoHS compliance, equivalent substitute parts with active or last-time-buy status are necessary for new designs and ongoing production requirements.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Manufacturer Part Number | 74FST3245QSR |
| Manufacturer | onsemi |
| Type | Bus Switch |
| Circuit Configuration | 8 x 1:1 |
| Voltage Supply Range | 4V ~ 5.5V |
| Operating Temperature Range | -40°C ~ 85°C |
| Package Type | 20-QSOP (0.154", 3.90mm Width) |
| Mounting Type | Surface Mount |
| Product Status | Obsolete |
| RoHS Status | Non-compliant |
| Moisture Sensitivity Level | 1 (Unlimited) |
Substitute Part Grouping Explanation
Substitution eligibility for the 74FST3245QSR is determined by the following critical parameters:
Functional Equivalence: All substitute parts must implement an 8-channel 1:1 bus switch configuration with identical circuit topology.
Electrical Compatibility: Voltage supply range must overlap or be compatible with the 4V to 5.5V requirement. Parts with supply ranges of 4V ~ 5.5V or 4.75V ~ 5.25V are functionally compatible.
Thermal Compatibility: Operating temperature range must support -40°C to 85°C operation.
Package Compatibility: Substitutes are grouped by package type. Parts in 20-QSOP, 20-TSSOP, and 20-SSOP packages are mechanically and electrically interchangeable with appropriate PCB layout modifications. Parts in 20-TVSOP packages require different footprint considerations.
Compliance Status: RoHS3-compliant alternatives are preferred for new designs. Product status (Active or Last Time Buy) indicates availability and long-term support.
Parameter Comparison
| Part Number | Manufacturer | Circuit | Voltage Supply | Temp Range | Package | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|
| 74FST3245QSR | onsemi | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-QSOP | Obsolete | Non-compliant |
| FST3245MTCX | onsemi | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP | Obsolete | ROHS3 Compliant |
| PI5C3245LE | Diodes Incorporated | 8 x 1:1 | 4.75V ~ 5.25V | -40°C ~ 85°C | 20-TSSOP | Last Time Buy | ROHS3 Compliant |
| PI5C3245LEX | Diodes Incorporated | 8 x 1:1 | 4.75V ~ 5.25V | -40°C ~ 85°C | 20-TSSOP | Last Time Buy | ROHS3 Compliant |
| PI5C3245QEX | Diodes Incorporated | 8 x 1:1 | 4.75V ~ 5.25V | -40°C ~ 85°C | 20-QSOP | Last Time Buy | ROHS3 Compliant |
| SN74CBT3245ADBR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP | Last Time Buy | ROHS3 Compliant |
| SN74CBT3245ADGVR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TVSOP | Last Time Buy | ROHS3 Compliant |
| SN74CBT3245APW | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP | Last Time Buy | ROHS3 Compliant |
| SN74CBT3245APWR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP | Last Time Buy | ROHS3 Compliant |
| SN74CBT3245CDBR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP | Active | ROHS3 Compliant |
| SN74CBT3245CDGVR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TVSOP | Active | ROHS3 Compliant |
Engineering Selection Recommendations
For Direct Package Replacement (20-QSOP): PI5C3245QEX from Diodes Incorporated provides the closest mechanical and electrical match. This part maintains the same 20-QSOP package footprint, operates within compatible voltage and temperature ranges, and carries RoHS3 compliance with Last Time Buy status.
For Voltage Supply Range Compatibility: Parts with 4V ~ 5.5V supply range (onsemi FST3245MTCX, Texas Instruments SN74CBT3245 series) provide full compatibility with the original 74FST3245QSR specification. Parts with 4.75V ~ 5.25V range (Diodes Incorporated PI5C3245 series) operate within a narrower window and require verification that system supply voltages remain within this tighter band.
For Active Production Status: SN74CBT3245CDBR and SN74CBT3245CDGVR from Texas Instruments are the only parts with Active product status, ensuring long-term availability and ongoing manufacturer support. These parts are suitable for new designs requiring extended production lifecycles.
For RoHS Compliance: All substitute parts listed carry RoHS3 compliance, addressing the non-compliant status of the original 74FST3245QSR. This is mandatory for applications subject to RoHS regulations.
For Packaging Flexibility: If PCB layout modifications are acceptable, 20-TSSOP packages (FST3245MTCX, PI5C3245LE, PI5C3245LEX, SN74CBT3245APW, SN74CBT3245APWR) offer the highest inventory availability across multiple manufacturers.
Frequently Asked Questions (FAQ)
Q: Can I use a 20-TSSOP package substitute in place of the 20-QSOP original?
A: Yes, with PCB layout modifications. Both packages are surface mount with 20 pins and identical electrical functionality. The 20-TSSOP has a slightly larger width (4.40mm vs 3.90mm). Verify that your PCB layout can accommodate the different footprint dimensions before proceeding.
Q: What is the difference between PI5C3245LE and PI5C3245LEX?
A: Both parts are functionally identical 8 x 1:1 bus switches from Diodes Incorporated with the same electrical specifications. The primary difference is packaging: PI5C3245LE is supplied in Tube packaging, while PI5C3245LEX is supplied in Tape & Reel format. Select based on your procurement and assembly requirements.
Q: Why do some substitutes have a narrower voltage supply range (4.75V ~ 5.25V)?
A: The Diodes Incorporated PI5C3245 series operates within a tighter voltage window compared to the original 74FST3245QSR (4V ~ 5.5V). Verify that your system power supply remains within the 4.75V to 5.25V range before selecting these parts. If your system requires operation below 4.75V or above 5.25V, use parts with the 4V ~ 5.5V specification.
Q: Which substitute should I choose for a new design?
A: For new designs, select SN74CBT3245CDBR or SN74CBT3245CDGVR from Texas Instruments. Both parts have Active product status, ensuring manufacturer support and long-term availability. Choose the package that best fits your PCB layout: 20-SSOP (SN74CBT3245CDBR) or 20-TVSOP (SN74CBT3245CDGVR).
Q: Are all substitute parts RoHS compliant?
A: Yes. All substitute parts listed carry RoHS3 compliance. The original 74FST3245QSR is RoHS non-compliant. If your application requires RoHS compliance, any of the listed substitutes will satisfy this requirement.
Q: What does "Last Time Buy" product status mean?
A: Last Time Buy indicates that the manufacturer has announced end-of-life for the part. Production will cease after a specified date, and no new orders will be accepted after that point. Parts with this status have limited availability. For long-term production requirements, prioritize parts with Active status.
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