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1SMC45AT3 Transient Voltage Suppressor Diode – Equivalent & Substitute Parts
Part Overview
The 1SMC45AT3 is a unidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 45V reverse standoff voltage, 72.2V maximum clamping voltage, and 20.6A peak pulse current capability in a DO-214AB (SMC) package. The part is currently classified as obsolete, making identification of active equivalent and substitute components essential for ongoing design support and procurement.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Manufacturer Part Number | 1SMC45AT3 |
| Manufacturer | onsemi |
| Category | Transient Voltage Suppressors (TVS) |
| Type | Zener |
| Unidirectional Channels | 1 |
| Voltage – Reverse Standoff (Typ) | 45V |
| Voltage – Breakdown (Min) | 50V |
| Voltage – Clamping (Max) @ Ipp | 72.2V |
| Current – Peak Pulse (10/1000µs) | 20.6A |
| Power – Peak Pulse | 1500W |
| Operating Temperature Range | -65°C to 150°C (TJ) |
| Package / Case | DO-214AB, SMC |
| Mounting Type | Surface Mount |
| Product Status | Obsolete |
| RoHS Status | RoHS non-compliant |
Substitute Part Grouping Explanation
Substitution of the 1SMC45AT3 is determined by the following critical electrical and mechanical parameters:
Primary Substitution Criteria:
- Voltage – Reverse Standoff: 45V (±tolerance)
- Voltage – Breakdown (Min): 50V
- Voltage – Clamping (Max) @ Ipp: 72.2V to 72.7V range
- Current – Peak Pulse (10/1000µs): 20.6A minimum
- Package / Case: DO-214AB (SMC)
- Unidirectional configuration: 1 channel
- Mounting Type: Surface Mount
Substitute parts are grouped into two categories:
Category A – Direct Electrical Equivalents (1500W Peak Pulse Power): Parts with matching 20.6A peak pulse current and 1500W power dissipation. These provide pin-for-pin and functional equivalence with the original component.
Category B – Enhanced Performance Alternatives (5000W Peak Pulse Power): Parts with higher peak pulse current (68.8A) and 5000W power dissipation. These maintain voltage parameters but offer increased transient energy handling capability, suitable for applications requiring higher surge protection margins.
Parameter Comparison
| Part Number | Manufacturer | Voltage – Reverse Standoff | Voltage – Clamping (Max) @ Ipp | Current – Peak Pulse | Power – Peak Pulse | Operating Temperature | Package | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|---|---|
| 1SMC45AT3 | onsemi | 45V | 72.2V | 20.6A | 1500W | -65°C to 150°C | DO-214AB (SMC) | Obsolete | RoHS non-compliant |
| 1SMC45A TR13 PBFREE | Central Semiconductor Corp | 45V | 72.7V | 20.6A | 1500W | -65°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| SMCJ45A-13-F | Diodes Incorporated | 45V | 72.7V | 20.6A | 1500W | -55°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| SMCJ45A-HR | Littelfuse Inc. | 45V | 72.7V | 20.6A | 1500W | -65°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| SMCJ45A-HRA | Littelfuse Inc. | 45V | 72.7V | 20.6A | 1500W | -65°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| SMCJ45A-HRAT7 | Littelfuse Inc. | 45V | 72.7V | 20.6A | 1500W | -65°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| SMCJ45A | Meritek | 45V | 72.7V | 20.63A | 1500W | -55°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| 5.0SMDJ45A | Taiwan Semiconductor Corporation | 45V | 72.7V | 68.8A | 5000W | -55°C to 175°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
| 5.0SMDJ45A-T7 | Littelfuse Inc. | 45V | 72.7V | 68.8A | 5000W | -65°C to 150°C | DO-214AB (SMC) | Active | ROHS3 Compliant |
Engineering Selection Recommendations
For Direct Replacement (Electrical and Mechanical Equivalence):
Select from Category A parts when the application requires identical electrical performance and the original 1500W peak pulse power rating is sufficient. All Category A substitutes are active products with ROHS3 compliance, addressing the RoHS non-compliance status of the obsolete 1SMC45AT3.
Primary Recommendation – 1SMC45A TR13 PBFREE (Central Semiconductor Corp): This part provides the closest functional match with identical voltage and current parameters. Active product status and ROHS3 compliance ensure long-term availability and regulatory compliance. Tape & Reel packaging supports automated assembly processes.
Secondary Recommendations – SMCJ45A-HR, SMCJ45A-HRA, SMCJ45A-HRAT7 (Littelfuse Inc.): These variants maintain the full -65°C to 150°C operating temperature range of the original component, matching the thermal specification exactly. All are active products with ROHS3 compliance. The -HR and -HRA series designations indicate high-reliability variants suitable for demanding applications.
Alternative – SMCJ45A-13-F (Diodes Incorporated): Provides equivalent electrical performance with active product status and ROHS3 compliance. Operating temperature range is -55°C to 150°C, which is acceptable for most general-purpose applications but does not extend to the full -65°C lower limit of the original.
For Enhanced Protection (Higher Transient Energy Handling):
Select from Category B parts when the application requires increased surge protection margin or experiences higher transient energy levels. These parts maintain identical voltage parameters while providing 3.3× higher peak pulse current and 5000W power dissipation.
Primary Recommendation – 5.0SMDJ45A-T7 (Littelfuse Inc.): Maintains the full -65°C to 150°C operating temperature range with ROHS3 compliance and active product status. Suitable for applications requiring enhanced transient protection without thermal specification compromise.
Alternative – 5.0SMDJ45A (Taiwan Semiconductor Corporation): Offers extended upper operating temperature to 175°C with ROHS3 compliance and active status. Peak pulse current of 68.8A provides significant protection margin. Operating temperature range is -55°C to 175°C.
Frequently Asked Questions (FAQ)
Q: Can I use a 5000W part (Category B) as a direct replacement for the 1500W original?
A: Yes. Category B parts maintain all voltage parameters (45V standoff, 72.7V clamping) and are mechanically compatible in the DO-214AB (SMC) package. The higher power rating provides additional transient energy handling capability without affecting normal circuit operation. This is a valid upgrade path for applications requiring enhanced protection.
Q: What is the difference between SMCJ45A-HR, SMCJ45A-HRA, and SMCJ45A-HRAT7?
A: All three are Littelfuse high-reliability variants with identical electrical specifications. The suffix designations indicate packaging and tape configuration variants. SMCJ45A-HRAT7 specifies T7 tape format. Selection depends on your assembly equipment compatibility and procurement requirements. Electrical performance is equivalent across all three.
Q: Why is the 1SMC45A TR13 PBFREE recommended as the primary substitute?
A: This part provides the closest functional equivalence with matching 20.6A peak pulse current, 1500W power rating, and -65°C to 150°C operating temperature range. It is an active product with ROHS3 compliance, ensuring long-term availability and regulatory compliance. The TR13 tape format supports standard automated assembly processes.
Q: Does the clamping voltage difference between 72.2V (original) and 72.7V (substitutes) affect circuit compatibility?
A: No. The 0.5V difference falls within normal manufacturing tolerance for TVS diodes and does not affect circuit protection performance. Both values maintain the specified voltage clamping function for the 45V standoff application.
Q: Are all substitute parts available in Tape & Reel packaging for automated assembly?
A: Most Category A and all Category B parts are available in Tape & Reel format. Verify specific packaging availability with your supplier. The 1SMC45A TR13 PBFREE, SMCJ45A-13-F, and all Littelfuse variants explicitly list Tape & Reel (TR) packaging. Meritek SMCJ45A packaging format should be confirmed with your distributor.
Q: What is the operating temperature consideration when selecting between -55°C and -65°C lower limits?
A: The original 1SMC45AT3 specifies -65°C minimum operating temperature. If your application requires operation at temperatures below -55°C, select substitutes maintaining the -65°C specification: 1SMC45A TR13 PBFREE, SMCJ45A-HR, SMCJ45A-HRA, SMCJ45A-HRAT7, or 5.0SMDJ45A-T7. For applications with -55°C minimum requirements, all substitutes are acceptable.
Q: Is RoHS compliance mandatory for my application?
A: The original 1SMC45AT3 is RoHS non-compliant. All recommended substitutes are ROHS3 compliant. If your application or supply chain requires RoHS compliance, all listed substitutes meet this requirement. If legacy RoHS non-compliant components are acceptable, the original part may still be sourced from existing inventory.
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