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Vishay General Semiconductor - Diodes Division SM8S18ATHE3/I
- Part No.:
- SM8S18ATHE3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AC
- Datasheet:
-
SM8S18ATHE3/I.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO218AC
- Quantity:
- Payment:
- Shipping:
Inventory:1,140
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Product details
Overview
SM8S18ATHE3/I from Vishay General Semiconductor is a unidirectional surface-mount PAR® transient voltage suppressor (TVS) designed for automotive load dump protection. It features a 20.0–22.1 V breakdown voltage (VBR), 29.2 V clamping voltage (VC) at 226 A peak pulse current, 6600 W peak pulse power (10/1000 μs), 175 °C maximum junction temperature, and DO-218AC package with heatsink-anode polarity.
For engineers reviewing the SM8S18ATHE3/I datasheet, SM8S18ATHE3/I pinout, SM8S18ATHE3/I application, or SM8S18ATHE3/I equivalent, this device is selected for high-reliability 12 V automotive power rail protection where ISO 7637-2 compliance, low leakage (<10 μA at 18.0 V), and AEC-Q101 qualification are mandatory design requirements.
Technical Context
This TVS diode uses passivated anisotropic rectifier technology to achieve stable clamping under repetitive surge stress at elevated temperatures. Its unidirectional configuration and heatsink-anode terminal assignment enable direct thermal coupling to PCB copper planes for sustained 8 W power dissipation at TC = 25 °C.
The device meets ISO 7637-2 load dump waveforms (including 10 ms exponential) and supports automotive-grade reliability with MSL Level 1 rating (245 °C reflow peak) and JESD 201 Class 2 whisker resistance. Its 0.90 °C/W junction-to-case thermal resistance ensures effective heat transfer in constrained board layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 20.0 / 21.1 / 22.1 V - defines minimum voltage at which device enters avalanche conduction during transients |
| VWM | 18.0 V - maximum continuous reverse operating voltage before significant leakage begins |
| VC @ IPPM | 29.2 V at 226 A - clamped voltage seen by protected circuit during 10/1000 μs surge |
| PPPM (10/1000 μs) | 6600 W - peak transient energy handling capacity without failure |
| TJ max | +175 °C - enables operation in under-hood environments without derating |
| IFSM | 700 A - single half-sine surge current rating (8.3 ms), critical for alternator load dump events |
| RθJC | 0.90 °C/W - allows precise thermal design when mounted on heatsinked PCB copper |
Pinout & Package
Package: DO-218AC - thermally enhanced surface-mount outline with metal heatsink tab serving as anode terminal; RoHS-compliant matte tin plating; UL 94 V-0 molding compound.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Lead 1 | Cathode | Connected to protected line (e.g., battery rail); carries transient current into device |
| Lead 2 / Metal Heatsink Tab | Anode | Must be soldered to large copper pour for thermal management; electrically tied to system ground |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive use including temperature cycling, HTRB, and ESD testing per stress test plan |
| Junction passivation optimized design | Reduces parameter drift over lifetime and improves stability under high-temperature bias conditions |
| ISO 7637-2 compliance | Guarantees robust performance against standardized automotive load dump and switching surge waveforms |
| MSL Level 1 rating | Enables standard SMT reflow without moisture-related popcorn failure risk |
| Low leakage at VWM | <10 μA at 18.0 V and 25 °C - minimizes standby power loss in always-on vehicle modules |
Applications
| Engine Control Unit (ECU) Power Input Protection | Body Control Module (BCM) Battery Rail Protection |
|---|---|
Use Scenario: Protects ECU 12 V input from alternator load dump surges during battery disconnect events. IC Role / Device Role / Timing Role: Unidirectional TVS clamps transient overvoltage within 1 ns to prevent damage to downstream DC/DC converters and microcontrollers. Use Value: Withstands 6600 W pulses while maintaining clamping voltage ≤29.2 V, ensuring safe operation of 36 V-rated input stages. |
Use Scenario: Shields BCM power domain from inductive switching transients generated by door lock actuators and lighting loads. IC Role / Device Role / Timing Role: Fast-response transient suppressor placed at main power entry point to limit voltage overshoot before LDO regulators. Use Value: 0.90 °C/W RθJC enables reliable thermal performance even with limited heatsinking area on multi-layer PCBs. |
| Advanced Driver Assistance Systems (ADAS) Camera Power Supply | Electric Power Steering (EPS) Motor Driver Protection |
Use Scenario: Safeguards image sensor and SerDes IC power rails in rear-view and surround-view cameras exposed to harsh vehicle electrical noise. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 12 V camera module input, coordinated with upstream fuse and downstream LC filtering. Use Value: AEC-Q101 qualification and 175 °C TJ max ensure long-term reliability in sealed, non-ventilated camera housings. |
Use Scenario: Protects gate drivers and current sense amplifiers in EPS motor control units from commutation-induced spikes. IC Role / Device Role / Timing Role: High-energy TVS placed across H-bridge supply rails to absorb inductive kickback from brushed or BLDC motors. Use Value: 700 A IFSM rating handles worst-case motor stall and reversal surges without degradation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SM8S18AHM3 | Same VBR, VC, and PPPM; HM3 suffix indicates halogen-free, matte tin finish, and enhanced MSL Level 1 robustness | Identical automotive load dump protection capability; preferred for new designs due to "Not For New Designs" status of HE3 variant | Select SM8S18AHM3 for production ramp or redesign where long-term component availability and updated material compliance are required |
| SMAJ18A | Lower PPPM (400 W), smaller SMA package, no heatsink tab, 150 °C TJ max | Suitable only for low-energy transients (e.g., ESD, minor switching noise); not rated for ISO 7637-2 load dump | Use SMAJ18A only in non-automotive, low-power applications where space constraints preclude DO-218AC mounting |
Compared with SM8S18ATHE3/I, SM8S18AHM3 offers identical electrical performance with improved manufacturability and lifecycle support, while SMAJ18A provides compact size at the cost of surge capacity and automotive qualification - making SM8S18AHM3 the recommended drop-in upgrade path.
Availability
SM8S18ATHE3/I is available at Aetrix Electronics and suitable for automotive electronics, industrial power supplies, and transportation control systems requiring stable component supply and traceable sourcing for legacy program support.
Supply support for SM8S18ATHE3/I includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in high-reliability diodes, MOSFETs, and passive components for automotive, industrial, and computing markets.
The SM8SxxAT family was engineered specifically for automotive load dump protection, combining high surge capability, AEC-Q101 qualification, and thermally optimized DO-218AC packaging to meet stringent under-hood environmental demands.
FAQ
What is the primary function of the SM8S18ATHE3/I in automotive circuits?
The SM8S18ATHE3/I functions as a unidirectional transient voltage suppressor that protects sensitive downstream electronics from high-energy voltage surges-especially alternator load dump events defined in ISO 7637-2. Its 6600 W peak pulse power rating and 29.2 V clamping voltage ensure robust safeguarding of 12 V power rails in ECUs, BCMS, and ADAS modules. The SM8S18ATHE3/I achieves this using passivated anisotropic rectifier technology and a thermally efficient DO-218AC package with heatsink-anode construction.
Is the SM8S18ATHE3/I qualified for automotive applications?
Yes, the SM8S18ATHE3/I is AEC-Q101 qualified and explicitly intended for automotive use, as confirmed by Vishay's documentation. It meets requirements for temperature cycling, high-temperature reverse bias (HTRB), and mechanical shock testing. The HE3 suffix denotes RoHS compliance and JESD 201 Class 2 whisker resistance-both essential for automotive manufacturing. The SM8S18ATHE3/I also satisfies MSL Level 1 and ISO 7637-2 surge immunity standards.
What does the "HE3" suffix mean in SM8S18ATHE3/I?
The "HE3" suffix in SM8S18ATHE3/I identifies a specific Vishay ordering variant: RoHS-compliant, AEC-Q101 qualified, matte tin-plated leads, and JESD 201 Class 2 whisker resistance. It is supplied in 13″ plastic tape-and-reel format (750 pcs/reel) with anode oriented toward sprocket holes. This suffix distinguishes it from non-automotive variants and confirms its suitability for high-reliability production environments. The SM8S18ATHE3/I is part of Vishay's legacy HE3-series TVS portfolio.
Can the SM8S18ATHE3/I replace the SM8S18AHM3 in existing designs?
No-while the SM8S18ATHE3/I and SM8S18AHM3 share identical electrical specifications (VBR, VC, PPPM, etc.), Vishay designates SM8S18ATHE3/I as "Not For New Designs" and recommends SM8S18AHM3 for new projects. The HM3 variant offers enhanced process control, halogen-free materials, and extended lifecycle support. The SM8S18ATHE3/I remains viable for legacy BOM continuity but should not be specified for new automotive designs where long-term supply assurance is required.
What thermal design considerations apply to the SM8S18ATHE3/I?
The SM8S18ATHE3/I requires direct thermal coupling of its metal heatsink tab (anode) to a substantial PCB copper area-ideally ≥250 mm²-to maintain junction temperature below 175 °C under sustained 8 W power dissipation. Its 0.90 °C/W junction-to-case thermal resistance assumes optimal mounting; insufficient copper or poor solder joint quality will cause thermal runaway. Thermal vias under the tab and inner-layer copper pours significantly improve performance. The SM8S18ATHE3/I datasheet provides detailed mounting pad layout guidance for DO-218AC.
SM8S18ATHE3/I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-218AC
- Series:
- PAR®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 226A
- Power - Peak Pulse:
- 6600W (6.6kW)
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-218AC
SM8S18ATHE3/I FAQ
1.How can I place an order for SM8S18ATHE3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S18ATHE3/I on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SM8S18ATHE3/I reliable?
The price and inventory of SM8S18ATHE3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S18ATHE3/I is usually 5 days.
3.What payment methods are accepted for SM8S18ATHE3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S18ATHE3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S18ATHE3/I?
SM8S18ATHE3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S18ATHE3/I order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SM8S18ATHE3/I?
For technical support, including SM8S18ATHE3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S18ATHE3/I requirements.
6.How does Aetrix verify that SM8S18ATHE3/I is sourced from the original manufacturer or authorized distributors?
All SM8S18ATHE3/I products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SM8S18ATHE3/I meets industry standards.
7.What is the process for return or replacement of SM8S18ATHE3/I?
All SM8S18ATHE3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S18ATHE3/I, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SM8S18ATHE3/I part is unused and in its original packaging.
Return procedure for SM8S18ATHE3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S18ATHE3/I Tags
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