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3KASMC28HE3/9AT Equivalent & Substitute Parts
Part Overview
The 3KASMC28HE3/9AT is a unidirectional transient voltage suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division, designed for surface mount applications in the DO-214AB (SMC) package. This component provides 28V reverse standoff voltage with 50V maximum clamping voltage and 60A peak pulse current capability, delivering 3kW peak pulse power dissipation. The part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain functional compatibility within specified electrical and mechanical parameters.
Substiute Parts
Key Parameters
| Parameter | Value | Unit |
|---|---|---|
| Voltage - Reverse Standoff (Typ) | 28 | V |
| Voltage - Breakdown (Min) | 31.1 | V |
| Voltage - Clamping (Max) @ Ipp | 50 | V |
| Current - Peak Pulse (10/1000µs) | 60 | A |
| Power - Peak Pulse | 3000 | W |
| Operating Temperature Range | -65 to 185 | °C |
| Package / Case | DO-214AB, SMC | — |
| Mounting Type | Surface Mount | — |
| Type | Zener | — |
| Unidirectional Channels | 1 | — |
| RoHS Status | ROHS3 Compliant | — |
| Grade | Automotive | — |
| Qualification | AEC-Q101 | — |
Substitute Part Grouping Explanation
Substitution of the 3KASMC28HE3/9AT is determined by strict adherence to the following electrical and mechanical parameters:
Primary Substitution Criteria:
- Voltage - Reverse Standoff: 28V (fixed requirement)
- Voltage - Breakdown (Min): 31.1V (fixed requirement)
- Unidirectional Channels: 1 (fixed requirement)
- Package / Case: DO-214AB, SMC (fixed requirement)
- Mounting Type: Surface Mount (fixed requirement)
- Type: Zener (fixed requirement)
Allowable Parameter Variations:
- Voltage - Clamping (Max) @ Ipp: 45V to 59V (acceptable range for transient suppression)
- Current - Peak Pulse (10/1000µs): 33A to 500A (dependent on application requirements)
- Power - Peak Pulse: 1500W to 22500W (dependent on application requirements)
- Operating Temperature Range: Minimum -55°C, Maximum 150°C to 175°C (acceptable for most applications)
- RoHS Status: ROHS3 Compliant or RoHS non-compliant (both acceptable for legacy applications)
Substitute parts must maintain the 28V standoff voltage and 31.1V minimum breakdown voltage to ensure proper circuit protection. Package compatibility (DO-214AB/SMC) is mandatory for PCB assembly without redesign. Clamping voltage, peak current, and power dissipation may vary based on specific circuit protection requirements.
Parameter Comparison
| Part Number | Manufacturer | Voltage - Reverse Standoff (V) | Voltage - Breakdown Min (V) | Voltage - Clamping Max @ Ipp (V) | Current - Peak Pulse (A) | Power - Peak Pulse (W) | Operating Temp (°C) | Package | RoHS Status | Product Status |
|---|---|---|---|---|---|---|---|---|---|---|
| 3KASMC28HE3/9AT | Vishay General Semiconductor | 28 | 31.1 | 50 | 60 | 3000 | -65 to 185 | DO-214AB, SMC | ROHS3 Compliant | Obsolete |
| SMLJ28E3/TR13 | Microchip Technology | 28 | 31.1 | 50 | 60 | 300 | -55 to 150 | DO-214AB, SMC | ROHS3 Compliant | Active |
| 1SMC28A TR13 TIN/LEAD | Central Semiconductor Corp | 28 | 31.1 | 45.4 | 33 | 1500 | -65 to 150 | DO-214AB, SMC | RoHS non-compliant | Active |
| 3.0SMC28A | Littelfuse Inc. | 28 | 31.1 | 59 | 470 | — | -65 to 150 | DO-214AB, SMC | ROHS3 Compliant | Active |
| 3.0SMCJ28A-13 | Diodes Incorporated | 28 | 31.1 | 45.4 | 66.1 | 3000 | -55 to 175 | DO-214AB, SMC | ROHS3 Compliant | Active |
| 3SMC28A TR13 PBFREE | Central Semiconductor Corp | 28 | 31.1 | 45.4 | 66 | 3000 | -65 to 150 | DO-214AB, SMC | ROHS3 Compliant | Active |
| 5.0SMDJ28A | Taiwan Semiconductor Corporation | 28 | 31.1 | 45.4 | 110 | 5000 | -55 to 175 | DO-214AB, SMC | ROHS3 Compliant | Active |
| 5.0SMDJ28A-T7 | Littelfuse Inc. | 28 | 31.1 | 45.4 | 110 | 5000 | -65 to 150 | DO-214AB, SMC | ROHS3 Compliant | Active |
| LNBTVS4-304S | STMicroelectronics | 28 | 30 | 45 | 334 | 22500 | -55 to 150 | DO-214AB, SMC | ROHS3 Compliant | Active |
| LNBTVS6-304S | STMicroelectronics | 28 | 30 | 45 | 500 | 22500 | -55 to 150 | DO-214AB, SMC | ROHS3 Compliant | Active |
| SM30T33AY | STMicroelectronics | 28 | 31.1 | 45.4 | 66.1 | 3000 | -55 to 175 | DO-214AB, SMC | ROHS3 Compliant | Active |
Engineering Selection Recommendations
Direct Electrical Equivalents (Identical Clamping Voltage and Current):
SMLJ28E3/TR13 (Microchip Technology) provides the closest electrical match with 50V clamping voltage and 60A peak pulse current. This part is ROHS3 compliant and active in production. The primary limitation is reduced power dissipation (300W versus 3000W), which may restrict application to lower-energy transient events.
Recommended Substitutes (Matched Power Dissipation):
3.0SMCJ28A-13 (Diodes Incorporated) and 3SMC28A TR13 PBFREE (Central Semiconductor Corp) both deliver 3000W peak pulse power matching the original specification. Both are ROHS3 compliant and active. The 3.0SMCJ28A-13 operates to 175°C junction temperature, extending thermal capability. The 3SMC28A TR13 PBFREE maintains the -65°C lower temperature limit of the original part.
5.0SMDJ28A-T7 (Littelfuse Inc.) and 5.0SMDJ28A (Taiwan Semiconductor Corporation) provide enhanced performance with 5000W peak pulse power and 110A peak current, suitable for applications requiring higher transient energy absorption. Both are ROHS3 compliant and active.
High-Performance Alternatives (Enhanced Current Handling):
LNBTVS4-304S and LNBTVS6-304S (STMicroelectronics) offer significantly higher peak pulse current (334A and 500A respectively) and 22500W power dissipation for demanding transient suppression applications. Both are ROHS3 compliant and active. These parts employ 8/20µs pulse measurement versus the standard 10/1000µs specification.
Automotive-Grade Option:
SM30T33AY (STMicroelectronics) carries automotive grade designation and AEC-Q101 qualification, matching the original part's automotive credentials. This part delivers 3000W power dissipation with 66.1A peak current and operates to 175°C junction temperature. ROHS3 compliant and active in production.
Legacy Compatibility:
1SMC28A TR13 TIN/LEAD (Central Semiconductor Corp) is RoHS non-compliant but remains active for applications requiring tin/lead solder compatibility. This part delivers 1500W power dissipation with 33A peak current.
Frequently Asked Questions (FAQ)
Q: Can I substitute the 3KASMC28HE3/9AT with any of these parts without circuit redesign?
A: Yes, provided the substitute part maintains the 28V reverse standoff voltage, 31.1V minimum breakdown voltage, and DO-214AB/SMC package format. All listed substitutes meet these core requirements. However, verify that the substitute's clamping voltage, peak current, and power dissipation are appropriate for your specific circuit protection requirements.
Q: What is the difference between clamping voltage variations (45V to 59V)?
A: Clamping voltage determines the maximum voltage the TVS diode allows across the protected circuit during a transient event. Lower clamping voltages (45V) provide tighter protection but may increase power dissipation. Higher clamping voltages (59V) allow slightly higher transient peaks but reduce power stress on the diode. Select based on your circuit's maximum allowable voltage during transient suppression.
Q: Why do some substitutes have significantly higher peak pulse current ratings?
A: Peak pulse current rating indicates the maximum transient current the diode can safely conduct. Higher ratings (334A, 500A) accommodate larger transient events without degradation. Select based on your circuit's expected transient current magnitude. Oversizing provides design margin but is not required if your circuit's transient current is lower.
Q: Are all substitutes RoHS compliant?
A: Most listed substitutes are ROHS3 compliant. The exception is 1SMC28A TR13 TIN/LEAD, which is RoHS non-compliant and uses tin/lead solder. Select ROHS3 compliant parts for new designs unless legacy compatibility is required.
Q: What is the significance of operating temperature range differences?
A: The original part operates to 185°C junction temperature, while most substitutes operate to 150°C or 175°C. For applications operating near maximum junction temperature, select substitutes with higher temperature ratings (3.0SMCJ28A-13 and 5.0SMDJ28A at 175°C, or SM30T33AY at 175°C). For standard applications, 150°C rating is typically sufficient.
Q: Can I use LNBTVS4-304S or LNBTVS6-304S as direct replacements?
A: These parts are functionally compatible but employ different pulse measurement standards (8/20µs versus 10/1000µs). They deliver significantly higher peak current and power dissipation, making them suitable for high-energy transient suppression applications. Verify that your circuit design accommodates the higher performance characteristics before substitution.
Q: Is SM30T33AY suitable for automotive applications?
A: Yes. SM30T33AY carries automotive grade designation and AEC-Q101 qualification, matching the original part's automotive credentials. This part is recommended for automotive circuit protection applications requiring equivalent qualification levels.
Q: What packaging format do all these substitutes use?
A: All listed substitutes use DO-214AB (SMC) surface mount package, ensuring direct PCB footprint compatibility with the original 3KASMC28HE3/9AT without layout modifications.
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