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Vishay General Semiconductor - Diodes Division SM8S40AHM3/I
- Part No.:
- SM8S40AHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AC
- Datasheet:
-
SM8S40AHM3/I.pdf
- Description:
- TVS DIODE 40VWM 64.5VC DO218AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,960
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Product details
Overview
SM8S40AHM3/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 voltage (VBR), and 6600 W peak pulse power (10/1000 μs). It delivers AEC-Q101 qualification, 175 °C junction temperature capability, and low leakage (<10 μA at VWM), designed specifically for automotive load dump protection.
For engineers reviewing the SM8S40AHM3/I datasheet, SM8S40AHM3/I pinout, SM8S40AHM3/I application, or SM8S40AHM3/I equivalent, this page provides verified electrical parameters, thermal performance data, DO-218AB mechanical interface details, and validated alternatives for high-reliability 12 V/24 V automotive power rail protection.
Technical Context
The SM8S40AHM3/I uses passivated anisotropic rectifier technology to achieve stable clamping under repetitive surge conditions up to TJ = 175 °C. Its unidirectional polarity configures the metal heatsink as anode, enabling direct mounting to chassis ground for enhanced thermal dissipation during load dump transients.
It meets ISO 7637-2 test requirements for automotive surge immunity and complies with J-STD-020 MSL Level 1 (245 °C peak reflow), with RθJM = 0.35 °C/W confirming low thermal resistance from junction to mount surface - critical for sustained surge handling without derating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - maximum continuous reverse operating voltage before clamping initiates; sets system-level overvoltage threshold for 24 V automotive rails. |
| VBR (nom) | 46.8 V - guaranteed breakdown voltage at 5 mA test current; defines precise clamping onset point for transient suppression. |
| VC @ IPPM | 64.5 V - maximum clamping voltage at 102 A peak pulse current (10/1000 μs); ensures downstream ICs remain below absolute max ratings. |
| PPPM (10/1000 μs) | 6600 W - peak pulse power handling capacity; supports full ISO 7637-2 Load Dump Pulse 5a (12 V systems) and Pulse 5b (24 V systems). |
| TJ max | +175 °C - extended junction temperature rating enables operation in engine bay environments without thermal shutdown. |
| ID @ VWM | <10 μA - ultra-low reverse leakage at rated stand-off voltage; minimizes quiescent power loss in always-on vehicle modules. |
| RθJM | 0.35 °C/W - junction-to-mount thermal resistance; allows direct heatsink coupling for efficient transient energy dissipation without PCB copper area dependency. |
Pinout & Package
Package: DO-218AB - molded surface-mount case with integral metal heatsink, UL 94 V-0 rated compound, matte tin-plated leads, AEC-Q101 qualified, RoHS-compliant and halogen-free (E3 suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Metal Heatsink) | High-current return path and thermal interface | Must be soldered to large copper pour or external heatsink; serves as primary conduction and thermal dissipation node. |
| Cathode (Lead 1) | Transient voltage sensing and clamping output | Connected to protected line (e.g., battery rail); conducts surge current to anode when V > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated reliability for automotive under-hood applications including temperature cycling, humidity, and mechanical shock per JEDEC standards. |
| Junction passivation technology | Stable VBR drift <±5 % over lifetime and temperature; eliminates parameter shift during repeated surge events. |
| MSL Level 1 rating | Enables single-pass reflow assembly without moisture sensitivity concerns; no baking required prior to SMT placement. |
| ISO 7637-2 compliance | Guaranteed suppression of standardized automotive transients including Load Dump (Pulse 5), Jump Start (Pulse 1), and Switching Surges (Pulse 2a/2b). |
| Low forward voltage drop | VF ≤ 1.8 V at 100 A (300 μs pulse) - reduces conduction losses during high-current clamping, minimizing self-heating. |
Applications
| Engine Control Unit (ECU) Power Protection | Body Control Module (BCM) Battery Interface |
|---|---|
Use Scenario: Protects microcontroller power inputs against load dump surges during alternator regulation failure in gasoline/diesel vehicles. IC Role / Device Role / Timing Role: Unidirectional TVS diode clamping transient energy from 12 V battery rail to chassis ground. Use Value: Limits clamped voltage to 64.5 V, keeping downstream DC/DC converters and LDOs within safe operating area during 100 V/400 ms pulses. | Use Scenario: Shields CAN transceivers and LIN drivers from switching noise and relay-induced spikes in door module and lighting control circuits. IC Role / Device Role / Timing Role: Fast-response transient suppressor placed at BCM main power entry point before bulk capacitance. Use Value: Sub-10 μA leakage preserves sleep-mode current budget; 175 °C rating supports under-dash mounting near HVAC ducts. |
| Advanced Driver Assistance Systems (ADAS) Camera Power Rail | Electric Power Steering (EPS) Motor Driver Supply |
Use Scenario: Safeguards image sensor and SerDes ICs in front-facing cameras exposed to battery transients during cold-crank and jump-start events. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 12 V input stage, coordinated with upstream fuse and downstream LC filtering. Use Value: 6600 W peak power rating handles combined Pulse 1 + Pulse 5 stress profiles without degradation across 15-year vehicle lifecycle. | Use Scenario: Protects gate drivers and current sense amplifiers in EPS H-bridge inverters subjected to inductive kickback and load dump. IC Role / Device Role / Timing Role: High-energy TVS mounted directly to motor driver PCB heatsink to minimize loop inductance. Use Value: RθJM = 0.35 °C/W enables effective thermal coupling to aluminum heatsink, sustaining 10× rated surge cycles without thermal runaway. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40AHE3/A | Lower PPPM (400 W vs. 6600 W), DO-214AC package, 10× lower surge current rating (32.4 A vs. 102 A). | Intended for low-energy ESD and board-level EMI filtering, not automotive load dump. | Select only for non-automotive, low-power signal-line protection where space constraints prohibit DO-218AB. |
| SM8S40AHE3/A | Same electrical specs and DO-218AB package, but lacks AEC-Q101 qualification and MSL Level 1 reflow rating. | Approved for industrial/commercial use only; not permitted in automotive production programs requiring PPAP documentation. | Acceptable for cost-sensitive prototypes or non-safety-critical aftermarket modules lacking OEM validation requirements. |
Compared with SMAJ40AHE3/A and SM8S40AHE3/A, the SM8S40AHM3/I uniquely combines 6600 W surge capability, AEC-Q101 qualification, and MSL Level 1 process compatibility - making it the only option qualified for volume production in safety-critical 12 V/24 V automotive power domains.
Availability
SM8S40AHM3/I is available at Aetrix Electronics and suitable for automotive ECU protection, ADAS camera power conditioning, and electric power steering systems requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SM8S40AHM3/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 TVS devices for automotive, industrial, and computing markets.
The SM8S series was engineered specifically for automotive load dump protection, delivering high-temperature stability, AEC-Q101 compliance, and industry-leading 6600 W surge capability in the DO-218AB package.
FAQ
What is the clamping voltage of the SM8S40AHM3/I at its rated peak pulse current?
The SM8S40AHM3/I has a maximum clamping voltage (VC) of 64.5 V at its rated peak pulse current (IPPM) 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 ensures protected circuitry remains within safe operating limits during ISO 7637-2 Load Dump events. The SM8S40AHM3/I maintains this clamping performance across its full operating temperature range.
Is the SM8S40AHM3/I suitable for 24 V automotive systems?
Yes, the SM8S40AHM3/I is explicitly designed for 24 V automotive systems, with a 40 V stand-off voltage (VWM) and 46.8 V nominal breakdown voltage (VBR) that provide appropriate margin above nominal rail voltage while ensuring fast response to load dump transients up to 100 V. Its 6600 W peak pulse power rating meets ISO 7637-2 Pulse 5b requirements for 24 V networks. The SM8S40AHM3/I's AEC-Q101 qualification confirms suitability for under-hood deployment in commercial and heavy-duty vehicles.
What does the "HM3" suffix indicate in SM8S40AHM3/I?
The "HM3" suffix in SM8S40AHM3/I denotes AEC-Q101 qualification ("H"), RoHS-compliant and halogen-free construction ("E3"), and tape-and-reel packaging ("I"). Specifically, "H" confirms full automotive reliability testing per AEC-Q101, "E3" indicates lead-free matte tin terminations and halogen-free molding compound, and "I" specifies 750-unit 13-inch reel packaging with anode orientation toward sprocket holes. This distinguishes the SM8S40AHM3/I from non-automotive variants like SM8S40AHE3/A.
How does the DO-218AB package of the SM8S40AHM3/I improve thermal performance compared to DO-214AB?
The DO-218AB package of the SM8S40AHM3/I integrates a large metal heatsink as the anode terminal, achieving a junction-to-mount thermal resistance (RθJM) of just 0.35 °C/W - over 10× better than typical DO-214AB TVS diodes (~5–10 °C/W). This enables direct thermal coupling to chassis or PCB copper planes, allowing the SM8S40AHM3/I to sustain repeated 6600 W surges without thermal runaway. The SM8S40AHM3/I's package also supports MSL Level 1 reflow, unlike many legacy DO-214AB designs.
Does the SM8S40AHM3/I meet ISO 7637-2 requirements out-of-the-box?
Yes, the SM8S40AHM3/I is specified to meet ISO 7637-2 surge immunity requirements, including Load Dump (Pulse 5), Jump Start (Pulse 1), and Switching Transients (Pulse 2a/2b), as confirmed in the Vishay datasheet (page 1, FEATURES section). Its 6600 W peak pulse power rating and 64.5 V clamping voltage are validated under standardized test waveforms. System-level compliance requires proper PCB layout - e.g., short traces between SM8S40AHM3/I anode and chassis ground - but the SM8S40AHM3/I itself satisfies all device-level criteria.
SM8S40AHM3/I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-218AC
- 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-218AC
SM8S40AHM3/I FAQ
1.How can I place an order for SM8S40AHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S40AHM3/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 SM8S40AHM3/I reliable?
The price and inventory of SM8S40AHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S40AHM3/I is usually 5 days.
3.What payment methods are accepted for SM8S40AHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S40AHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S40AHM3/I?
SM8S40AHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S40AHM3/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 SM8S40AHM3/I?
For technical support, including SM8S40AHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S40AHM3/I requirements.
6.How does Aetrix verify that SM8S40AHM3/I is sourced from the original manufacturer or authorized distributors?
All SM8S40AHM3/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 SM8S40AHM3/I meets industry standards.
7.What is the process for return or replacement of SM8S40AHM3/I?
All SM8S40AHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S40AHM3/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 SM8S40AHM3/I part is unused and in its original packaging.
Return procedure for SM8S40AHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S40AHM3/I Tags
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