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74FST3245DTR2 Equivalent & Substitute Parts
Part Overview
The 74FST3245DTR2 is an 8x1:1 bus switch logic IC manufactured by onsemi in a 20-TSSOP package. This component functions as a high-speed multiplexer for digital signal routing in logic applications. The part is currently obsolete, making equivalent and substitute parts necessary for ongoing design support, maintenance, and new production requirements. Substitute parts must maintain functional equivalence through matching circuit topology, electrical specifications, and package compatibility.
Substiute Parts
Key Parameters
| Parameter | Specification |
|---|---|
| Type | Bus Switch |
| Circuit Configuration | 8 x 1:1 |
| Independent Circuits | 1 |
| Voltage Supply | Single Supply |
| Supply Voltage Range | 4V ~ 5.5V |
| Operating Temperature Range | -40°C ~ 85°C |
| Mounting Type | Surface Mount |
| Package / Case | 20-TSSOP (0.173", 4.40mm Width) |
| RoHS Status | RoHS non-compliant |
| Moisture Sensitivity Level | 1 (Unlimited) |
Substitute Part Grouping Explanation
Substitution for the 74FST3245DTR2 is determined by the following critical parameters:
- Circuit Type & Configuration: All substitutes must be 8x1:1 bus switches with single supply operation
- Voltage Supply Range: Acceptable range is 4V ~ 5.5V (note: PI5C3245 variants operate at 4.75V ~ 5.25V, a subset of this range)
- Operating Temperature: Must support -40°C ~ 85°C
- Package Compatibility: Primary substitutes use 20-TSSOP or equivalent 20-pin surface mount packages; 20-SSOP and 20-QSOP variants are functionally equivalent but require PCB layout adjustment
- Mounting Type: Surface mount only
Substitutes are grouped into two categories:
Category 1 - Direct Package Match (20-TSSOP): FST3245MTCX, PI5C3245LE, PI5C3245LEX, SN74CBT3245APW. These require no PCB modification.
Category 2 - Functional Equivalents (Alternative Packages): SN74CBT3245ADBQR, SN74CBT3245ADBR, SN74CBT3245ADGVR, SN74CBT3245CDBQR, SN74CBT3245CDBR, PI5C3245QEX. These maintain electrical function but use 20-SSOP or 20-QSOP packages with different pin pitch or body dimensions.
Parameter Comparison
| Part Number | Manufacturer | Circuit | Supply Voltage | Temp Range | Package | RoHS Status | Product Status | Inventory |
|---|---|---|---|---|---|---|---|---|
| 74FST3245DTR2 | onsemi | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP | Non-compliant | Obsolete | 2025 Pcs |
| FST3245MTCX | onsemi | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP | ROHS3 Compliant | Obsolete | 20498 Pcs |
| PI5C3245LE | Diodes Incorporated | 8 x 1:1 | 4.75V ~ 5.25V | -40°C ~ 85°C | 20-TSSOP | ROHS3 Compliant | Last Time Buy | 1417 Pcs |
| PI5C3245LEX | Diodes Incorporated | 8 x 1:1 | 4.75V ~ 5.25V | -40°C ~ 85°C | 20-TSSOP | ROHS3 Compliant | Last Time Buy | 1498 Pcs |
| PI5C3245QEX | Diodes Incorporated | 8 x 1:1 | 4.75V ~ 5.25V | -40°C ~ 85°C | 20-QSOP | ROHS3 Compliant | Last Time Buy | 9262 Pcs |
| SN74CBT3245APW | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TSSOP | ROHS3 Compliant | Last Time Buy | 2152 Pcs |
| SN74CBT3245ADBQR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP | ROHS3 Compliant | Last Time Buy | 2400 Pcs |
| SN74CBT3245ADBR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP | ROHS3 Compliant | Last Time Buy | 2200 Pcs |
| SN74CBT3245ADGVR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-TVSOP | ROHS3 Compliant | Last Time Buy | 2708 Pcs |
| SN74CBT3245CDBQR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP | ROHS3 Compliant | Active | 3643 Pcs |
| SN74CBT3245CDBR | Texas Instruments | 8 x 1:1 | 4V ~ 5.5V | -40°C ~ 85°C | 20-SSOP | ROHS3 Compliant | Active | 3039 Pcs |
Engineering Selection Recommendations
For Direct Replacement (No PCB Modification Required):
FST3245MTCX is the primary parametric equivalent, offering identical electrical specifications and 20-TSSOP package matching. This part is ROHS3 compliant and maintains the full 4V ~ 5.5V supply voltage range. Inventory availability is substantial at 20498 units.
SN74CBT3245APW (Texas Instruments) provides an alternative with identical package and electrical specifications, ROHS3 compliance, and active product support status. This part is suitable for new designs requiring long-term availability.
PI5C3245LE and PI5C3245LEX (Diodes Incorporated) are functionally equivalent with 20-TSSOP packaging but operate within a narrower voltage range (4.75V ~ 5.25V). These are suitable only if the application supply voltage is constrained to this range. Both are ROHS3 compliant.
For Functional Equivalence (PCB Layout Adjustment Required):
SN74CBT3245CDBQR and SN74CBT3245CDBR (Texas Instruments) are active products with ROHS3 compliance, offering the longest product lifecycle. These use 20-SSOP packaging with different pin pitch (0.154" or 0.209" width) and require PCB footprint modification.
SN74CBT3245ADBQR and SN74CBT3245ADBR provide similar functional equivalence in 20-SSOP packages with last-time-buy status.
SN74CBT3245ADGVR uses a 20-TVSOP package (0.173" width, similar to TSSOP) and may be suitable with minor footprint verification.
PI5C3245QEX (Diodes Incorporated) offers the highest inventory availability (9262 units) but uses a 20-QSOP package with different body dimensions (0.154" width) and requires PCB redesign.
Compliance Consideration:
All substitute parts are ROHS3 compliant, addressing the non-compliant status of the original 74FST3245DTR2. This is advantageous for new production and regulatory requirements.
Frequently Asked Questions (FAQ)
Q: Can I use PI5C3245LE as a direct replacement for 74FST3245DTR2?
A: PI5C3245LE is functionally equivalent with matching 20-TSSOP package and circuit configuration. However, its supply voltage range (4.75V ~ 5.25V) is narrower than the original (4V ~ 5.5V). Use this part only if your application operates within the 4.75V ~ 5.25V window.
Q: What is the difference between 20-TSSOP, 20-SSOP, and 20-QSOP packages?
A: All are 20-pin surface mount packages with different body widths and pin pitch. 20-TSSOP (0.173" width) and 20-TVSOP match the original footprint. 20-SSOP variants (0.154" or 0.209" width) and 20-QSOP (0.154" width) require PCB layout modification. Pin-to-pin electrical function remains identical.
Q: Is SN74CBT3245CDBQR suitable for new designs?
A: Yes. SN74CBT3245CDBQR is an active product with ROHS3 compliance and long-term availability. It requires a 20-SSOP footprint (0.154" width) instead of 20-TSSOP, necessitating PCB redesign.
Q: Why does FST3245MTCX have higher inventory than the original part?
A: FST3245MTCX is the current production equivalent from onsemi with ROHS3 compliance. Higher inventory reflects ongoing manufacturing and distribution.
Q: Can I mix different substitute parts in the same design?
A: All listed substitutes are functionally equivalent for the 8x1:1 bus switch circuit. However, use consistent part numbers within a single PCB design to avoid assembly and testing complications. Different packages require different footprints.
Q: What is the significance of "Last Time Buy" status?
A: Last Time Buy indicates the manufacturer will discontinue the part after a specified date. Parts with this status have limited availability windows. For long-term production, prioritize active products like SN74CBT3245CDBQR or SN74CBT3245CDBR.
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