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1SMC18AT3 Equivalent & Substitute Parts
Part Overview
The 1SMC18AT3 is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by onsemi, rated for 18V reverse standoff voltage with a 29.2V clamping voltage at peak pulse current of 51.4A. This component is designed for general-purpose transient voltage suppression in surface mount applications using the DO-214AB (SMC) package. The part is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and production requirements.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Manufacturer Part Number | 1SMC18AT3 |
| Manufacturer | onsemi |
| Category | Transient Voltage Suppressors (TVS) |
| Type | Zener |
| Unidirectional Channels | 1 |
| Voltage - Reverse Standoff (Typ) | 18V |
| Voltage - Breakdown (Min) | 20V |
| Voltage - Clamping (Max) @ Ipp | 29.2V |
| Current - Peak Pulse (10/1000µs) | 51.4A |
| Power - Peak Pulse | 1500W |
| Package / Case | DO-214AB, SMC |
| Mounting Type | Surface Mount |
| Operating Temperature | -65°C ~ 150°C (TJ) |
| Product Status | Obsolete |
| RoHS Status | RoHS non-compliant |
Substitute Part Grouping Explanation
Substitution for the 1SMC18AT3 is determined by strict electrical and mechanical parameter matching:
Critical Parameters for Substitution:
- Voltage - Reverse Standoff (Typ): 18V
- Voltage - Breakdown (Min): 20V
- Voltage - Clamping (Max) @ Ipp: 29.2V
- Current - Peak Pulse (10/1000µs): 51.4A
- Power - Peak Pulse: 1500W
- Package / Case: DO-214AB, SMC
- Unidirectional Channels: 1
Substitute parts are grouped into two categories:
Direct Equivalents: Parts with identical electrical specifications (18V standoff, 29.2V clamping, 51.4A peak pulse, 1500W peak power) in the same DO-214AB/SMC package. These parts are pin-compatible and functionally interchangeable.
Similar Parts with Enhanced Specifications: Parts with identical voltage ratings and package but higher peak pulse current (172A) and peak power (5000W). These parts provide superior transient suppression capability and are backward-compatible for applications requiring the 1SMC18AT3 specifications.
Parameter Comparison
| Parameter | 1SMC18AT3 (onsemi) | SMCJ18A (MDD) | 5.0SMDJ18A (TSC) | 5.0SMDJ18A-T7 (Littelfuse) | SMCJ18A-13-F (Diodes) | SMCJ18A-HR (Littelfuse) | SMCJ18A-HRA (Littelfuse) | SMCJ18A-HRAT7 (Littelfuse) | SMCJ18A-M3/57T (Vishay) |
|---|---|---|---|---|---|---|---|---|---|
| Voltage - Reverse Standoff (Typ) | 18V | 18V | 18V | 18V | 18V | 18V | 18V | 18V | 18V |
| Voltage - Breakdown (Min) | 20V | 20V | 20V | 20V | 20V | 20V | 20V | 20V | 20V |
| Voltage - Clamping (Max) @ Ipp | 29.2V | 29.2V | 29.2V | 29.2V | 29.2V | 29.2V | 29.2V | 29.2V | 29.2V |
| Current - Peak Pulse (10/1000µs) | 51.4A | 51.4A | 172A | 172A | 51.4A | 51.4A | 51.4A | 51.4A | 51.4A |
| Power - Peak Pulse | 1500W | 1500W | 5000W | 5000W | 1500W | 1500W | 1500W | 1500W | 1500W |
| Package / Case | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC | DO-214AB, SMC |
| Mounting Type | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount |
| Operating Temperature | -65°C ~ 150°C | -50°C ~ 150°C | -55°C ~ 175°C | -65°C ~ 150°C | -55°C ~ 150°C | -65°C ~ 150°C | -65°C ~ 150°C | -65°C ~ 150°C | -55°C ~ 150°C |
| Product Status | Obsolete | Active | Active | Active | Active | Active | Active | Active | Active |
| RoHS Status | RoHS non-compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant |
Engineering Selection Recommendations
Direct Equivalent Selection (Identical Specifications):
SMCJ18A (MDD) is the primary direct equivalent, offering identical electrical performance with active product status and ROHS3 compliance. This part is recommended for designs requiring exact specification matching with modern manufacturing standards.
SMCJ18A-13-F (Diodes Incorporated), SMCJ18A-HR (Littelfuse), SMCJ18A-HRA (Littelfuse), and SMCJ18A-HRAT7 (Littelfuse) are functionally equivalent alternatives with identical voltage and current ratings. All are active products with ROHS3 compliance. Selection among these parts may be based on supplier availability, packaging preference (Tape & Reel vs. bulk), or existing supply chain relationships.
SMCJ18A-M3/57T (Vishay General Semiconductor) provides equivalent performance in the TransZorb® series with ROHS3 compliance and active product status.
Enhanced Specification Selection (Higher Current/Power Rating):
5.0SMDJ18A (Taiwan Semiconductor Corporation) and 5.0SMDJ18A-T7 (Littelfuse) offer superior transient suppression with 172A peak pulse current and 5000W peak power while maintaining identical voltage ratings. These parts are backward-compatible with the 1SMC18AT3 specification and provide enhanced protection margins. Both are active products with ROHS3 compliance. Selection between these two depends on operating temperature requirements (TSC: -55°C to 175°C; Littelfuse: -65°C to 150°C) and packaging format preference.
All substitute parts are ROHS3 compliant, addressing the non-compliance status of the obsolete 1SMC18AT3.
Frequently Asked Questions (FAQ)
Q: Can SMCJ18A (MDD) be used as a direct replacement for 1SMC18AT3?
A: Yes. SMCJ18A matches all critical electrical parameters: 18V reverse standoff, 20V breakdown minimum, 29.2V clamping voltage, and 51.4A peak pulse current. Both use the DO-214AB/SMC package with identical pinout. The part is pin-compatible and functionally interchangeable.
Q: What is the difference between the 1500W and 5000W rated parts?
A: The 1500W parts (SMCJ18A series) match the original 1SMC18AT3 power rating exactly. The 5000W parts (5.0SMDJ18A series) provide higher peak pulse power dissipation capability while maintaining identical voltage specifications. Both are suitable for applications designed around the 1SMC18AT3, with the 5000W parts offering additional transient suppression margin.
Q: Are all substitute parts RoHS compliant?
A: Yes. All listed substitute parts are ROHS3 compliant, addressing the RoHS non-compliant status of the obsolete 1SMC18AT3. This compliance is required for most modern manufacturing and procurement standards.
Q: Does operating temperature range affect part selection?
A: Operating temperature ranges vary slightly among substitutes. The 1SMC18AT3 operates from -65°C to 150°C. SMCJ18A (MDD) operates from -50°C to 150°C, which is narrower. For applications requiring the full -65°C lower limit, select SMCJ18A-HR, SMCJ18A-HRA, SMCJ18A-HRAT7 (Littelfuse), or 5.0SMDJ18A-T7 (Littelfuse). The 5.0SMDJ18A (TSC) extends to -55°C and 175°C upper limit.
Q: What packaging options are available?
A: All substitute parts use the DO-214AB/SMC surface mount package, maintaining mechanical compatibility. Packaging format varies: some are supplied in Tape & Reel (TR) format for automated assembly, while others are available in bulk. Verify packaging preference with your supplier before ordering.
Q: Can I use SMCJ18A-13-F as a substitute?
A: Yes. SMCJ18A-13-F (Diodes Incorporated) provides identical electrical specifications with 51.4A peak pulse current and 1500W power rating. It is ROHS3 compliant and active. The "-13-F" suffix indicates the specific product variant; electrical performance is equivalent to other SMCJ18A variants.
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