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Vishay General Semiconductor - Diodes Division SM8S40AHE3_A/I
- Part No.:
- SM8S40AHE3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
SM8S40AHE3_A/I.pdf
- Description:
- TVS DIODE 40VWM 64.5VC DO218AB
- Quantity:
- Payment:
- Shipping:
Inventory:4,055
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Product details
Overview
SM8S40AHE3_A/I from Vishay General Semiconductor is a unidirectional surface-mount PAR® transient voltage suppressor in DO-218AB package, rated for 40 V stand-off voltage (VWM), 46.8 V nominal breakdown (VBR), 64.5 V clamping voltage (VC) at 102 A peak pulse current, and 6600 W peak pulse power (10/1000 μs). It is AEC-Q101 qualified and designed for automotive load dump protection.
For engineers reviewing the SM8S40AHE3_A/I datasheet, SM8S40AHE3_A/I pinout, SM8S40AHE3_A/I application, or SM8S40AHE3_A/I equivalent, this page delivers verified electrical parameters, thermal performance data, automotive qualification status, and direct alternative part guidance - all specific to SM8S40AHE3_A/I and its DO-218AB mechanical implementation.
Technical Context
This TVS diode uses passivated anisotropic rectifier technology to achieve low leakage (<10 μA at VWM), low forward voltage drop (≤1.8 V at 100 A), and stable operation up to TJ = 175 °C. Its junction-to-mount thermal resistance is 0.35 °C/W, enabling high-power transient suppression on thermally optimized PCBs with metal heatsink mounting.
The device meets ISO 7637-2 surge requirements under defined test conditions and complies with MSL Level 1 (245 °C reflow peak). Polarity is fixed: anode is the metal heatsink terminal, cathode is lead 1 - critical for correct PCB layout and thermal path design.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - maximum continuous reverse operating voltage before clamping begins; defines system bus voltage compatibility. |
| VBR (nom) | 46.8 V - nominal breakdown voltage at 5 mA test current; ensures reliable triggering above normal transients. |
| VC @ IPPM | 64.5 V - clamping voltage at 102 A (10/1000 μs); determines protected circuit's maximum overvoltage exposure. |
| PPPM (10/1000 μs) | 6600 W - peak pulse power handling; supports high-energy load dump events per ISO 7637-2. |
| TJ max | +175 °C - maximum junction temperature; enables under-hood automotive deployment without derating. |
| RθJM | 0.35 °C/W - junction-to-mount thermal resistance; requires direct metal heatsink contact for full power rating. |
| Polarity | Unidirectional - blocks reverse voltage only; anode connected to system ground or low-side reference. |
Pinout & Package
Package: DO-218AB - surface-mount, single-ended metal heatsink package with matte tin-plated leads; anode is the exposed metal base (heatsink), cathode is lead 1; meets UL 94 V-0 and JESD 201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Metal Heatsink) | Current return path & thermal interface | Must be soldered to large copper pour or dedicated heatsink; electrically connects to system ground or low-side rail. |
| Cathode (Lead 1) | Transient current input terminal | Connects to protected line (e.g., battery feed); clamps positive surges to anode potential. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD; required for Tier 1 supply chain acceptance. |
| Junction passivation | Stable VBR drift <±0.092 %/°C; ensures predictable clamping across -55 °C to +175 °C ambient range. |
| Low leakage at VWM | <10 μA at 40 V and 25 °C; minimizes standby power loss in always-on vehicle modules. |
| High IFSM rating | 700 A peak forward surge (8.3 ms half-sine); withstands repetitive cranking-induced transients without degradation. |
| MSL Level 1 | Rated for 245 °C peak reflow profile; supports standard SMT assembly without moisture sensitivity concerns. |
Applications
| Automotive Load Dump Protection | Engine Control Unit (ECU) Power Input |
|---|---|
|
Use Scenario: Suppresses 12 V system load dump transients (up to 120 V, 400 ms) during alternator field-circuit disconnection. IC Role / Device Role / Timing Role: Primary clamping device placed between battery rail and DC/DC converter input. Use Value: Limits voltage seen by downstream regulators to ≤64.5 V, preventing overvoltage shutdown or damage during ISO 7637-2 Test Pulse 5a. |
Use Scenario: Protects microcontroller and sensor power supplies in engine bay ECUs exposed to cranking dips and ignition noise. IC Role / Device Role / Timing Role: Unidirectional TVS shunting positive spikes on 12 V main input before LDO or buck regulator. Use Value: Withstands 700 A surge (8.3 ms) without failure, ensuring ECU remains operational during repeated start-stop cycles. |
| Body Control Module (BCM) Power Rail | ADAS Camera Power Interface |
|
Use Scenario: Guards BCM power inputs against inductive switching transients from relays, motors, and solenoids. IC Role / Device Role / Timing Role: Fast-response clamping element on fused 12 V distribution lines feeding multiple subsystems. Use Value: 6600 W peak power rating handles simultaneous transients from multiple loads; low VBR tolerance (±5 %) ensures consistent trip point across production lots. |
Use Scenario: Shields 12 V camera module power input from hot-swap and cable discharge events in rear-view or surround-view systems. IC Role / Device Role / Timing Role: First-line transient suppressor mounted adjacent to connector, before EMI filter and DC/DC stage. Use Value: DO-218AB metal heatsink enables direct thermal coupling to chassis ground, maintaining clamping performance at +105 °C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SM8S40AHM3_A/I | Same VWM/VBR/VC ratings and DO-218AB package; HM3 suffix indicates updated internal construction and enhanced robustness per newer AEC-Q101 revision. | Identical use cases; preferred for new designs due to improved surge lifetime and tighter parametric consistency. | Select SM8S40AHM3_A/I for new designs requiring long-term supply continuity and latest qualification baseline. |
| SMAJ40A | Lower PPPM (400 W vs. 6600 W), smaller SMA package (RθJA = 110 °C/W), no AEC-Q101 qualification, and lower IFSM (40 A). | Limited to low-energy consumer or industrial applications; unsuitable for automotive load dump or high-reliability environments. | Use SMAJ40A only in non-automotive, low-surge contexts where space constraints outweigh power handling needs. |
Compared with SM8S40AHE3_A/I, SM8S40AHM3_A/I offers identical electrical specs with enhanced process control and qualification coverage, while SMAJ40A trades substantial power and reliability for footprint reduction - making SM8S40AHE3_A/I the optimal balance of automotive compliance, thermal capability, and surge margin for under-hood 12 V systems.
Availability
SM8S40AHE3_A/I is available at Aetrix Electronics and suitable for automotive load dump protection, engine control unit (ECU) power input, and body control module (BCM) power rail applications requiring stable component supply and long-term lifecycle support.
Supply support for SM8S40AHE3_A/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 SM8SxxA series is engineered specifically for high-energy automotive transient suppression, emphasizing AEC-Q101 qualification, 175 °C operation, and DO-218AB thermal performance - targeting under-hood power rail protection.
FAQ
What is the clamping voltage of SM8S40AHE3_A/I at its rated peak pulse current?
The SM8S40AHE3_A/I has a maximum clamping voltage (VC) of 64.5 V when subjected to its rated peak pulse current of 102 A under the 10/1000 μs waveform. This value is measured per standard test conditions in the Vishay datasheet (Document Number 88387, Page 2) and defines the upper voltage limit imposed on protected circuitry during surge events.
Is SM8S40AHE3_A/I suitable for new automotive designs?
No - SM8S40AHE3_A/I is marked "Not For New Designs" in the official Vishay documentation, with SM8S40AHM3_A/I designated as the recommended alternative. While SM8S40AHE3_A/I remains available and fully functional, new designs should use SM8S40AHM3_A/I to ensure long-term supply, updated qualification, and enhanced robustness per latest AEC-Q101 revisions.
How is polarity configured on SM8S40AHE3_A/I, and why does it matter?
SM8S40AHE3_A/I is unidirectional, with the metal heatsink serving as the anode and lead 1 as the cathode. Correct polarity is critical: reversing connection prevents clamping action and risks catastrophic failure during transients. The anode must connect to the system reference (e.g., ground or low-side rail) to enable proper surge shunting.
What thermal mounting requirements apply to SM8S40AHE3_A/I?
SM8S40AHE3_A/I requires direct thermal contact between its metal heatsink (anode) and a large copper area or external heatsink to achieve its rated 6600 W peak pulse power. Its RθJM is 0.35 °C/W - meaning insufficient copper area or poor solder joint quality will cause junction overheating and premature failure during high-energy surges.
Does SM8S40AHE3_A/I meet ISO 7637-2, and under what conditions?
Yes - SM8S40AHE3_A/I meets ISO 7637-2 surge requirements, specifically for Test Pulse 5a (load dump), as confirmed in the Vishay datasheet. Compliance is validated under defined test conditions including 10 ms exponential waveform, 12 V nominal system voltage, and specified source impedance; actual system-level validation remains the designer's responsibility.
SM8S40AHE3_A/I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-218AB
- Series:
- PAR®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 64.5V
- Current - Peak Pulse (10/1000µs):
- 102A
- 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-218AB
SM8S40AHE3_A/I FAQ
1.How can I place an order for SM8S40AHE3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S40AHE3_A/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 SM8S40AHE3_A/I reliable?
The price and inventory of SM8S40AHE3_A/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S40AHE3_A/I is usually 5 days.
3.What payment methods are accepted for SM8S40AHE3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S40AHE3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S40AHE3_A/I?
SM8S40AHE3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S40AHE3_A/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 SM8S40AHE3_A/I?
For technical support, including SM8S40AHE3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S40AHE3_A/I requirements.
6.How does Aetrix verify that SM8S40AHE3_A/I is sourced from the original manufacturer or authorized distributors?
All SM8S40AHE3_A/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 SM8S40AHE3_A/I meets industry standards.
7.What is the process for return or replacement of SM8S40AHE3_A/I?
All SM8S40AHE3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S40AHE3_A/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 SM8S40AHE3_A/I part is unused and in its original packaging.
Return procedure for SM8S40AHE3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S40AHE3_A/I Tags
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