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Vishay General Semiconductor - Diodes Division SM8S18AHM3/I
- Part No.:
- SM8S18AHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AC
- Datasheet:
-
SM8S18AHM3/I.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO218AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,322
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Product details
Overview
SM8S18AHM3/I from Vishay General Semiconductor is a unidirectional surface-mount PAR® transient voltage suppressor in DO-218AB package, rated for 18 V stand-off voltage (VWM), 20.0–22.1 V breakdown voltage (VBR) at 5 mA, 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), targeting automotive load dump protection.
For engineers reviewing the SM8S18AHM3/I datasheet, SM8S18AHM3/I pinout, SM8S18AHM3/I application, or SM8S18AHM3/I equivalent, this page provides verified electrical parameters, thermal resistance (RθJM = 0.35 °C/W), clamping behavior (VC = 29.2 V at IPPM), polarity configuration (anode-heatsink), and direct alternatives aligned with Vishay's official replacement guidance.
Technical Context
This TVS diode employs passivated anisotropic rectifier technology to achieve stable clamping under high-energy transients while maintaining low forward voltage drop (≤1.8 V at 100 A) and minimal leakage across its full operating temperature range (−55 °C to +175 °C). Its DO-218AB package integrates a metal heatsink as the anode terminal, enabling efficient thermal transfer to PCB copper.
The device meets ISO 7637-2 surge requirements for automotive load dump events and complies with MSL Level 1 (245 °C reflow peak). Its 0.35 °C/W junction-to-mount thermal resistance supports high-power transient dissipation without external heatsinking when mounted on adequate copper area.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18.0 V - Maximum continuous reverse voltage before clamping begins; defines safe operating margin below system rail. |
| VBR (min/typ/max) | 20.0 / 21.1 / 22.1 V at 5 mA - Confirmed breakdown threshold ensures predictable turn-on during overvoltage events. |
| VC at IPPM | 29.2 V - Clamped voltage under 6600 W (10/1000 μs) surge; determines maximum stress on downstream ICs. |
| PPPM (10/1000 μs) | 6600 W - Peak transient energy handling capacity; enables robust protection against ISO 7637-2 load dump pulses. |
| IFSM | 700 A - Non-repetitive forward surge rating; supports high-current inductive switching transients. |
| TJ max | +175 °C - Enables operation in under-hood automotive environments without derating. |
| RθJM | 0.35 °C/W - Junction-to-mount thermal resistance; allows accurate thermal modeling when heatsinked to PCB copper. |
Pinout & Package
Package: DO-218AB - Surface-mount molded case with integral metal heatsink acting as anode terminal; meets UL 94 V-0, RoHS-compliant, AEC-Q101 qualified, matte tin-plated leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Heatsink) | Current entry point during clamping | Electrically connected to metal base; must be soldered to large copper pour for thermal and electrical performance. |
| Cathode (Lead 1) | Current exit point during clamping | Standard signal-side connection; routed to protected line (e.g., 12 V battery rail). |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated reliability for automotive under-hood applications including temperature cycling, humidity, and mechanical shock. |
| Junction passivation | Stable VBR drift <0.083 %/°C and low leakage (<10 μA at VWM, 175 °C) ensure long-term clamping consistency. |
| DO-218AB metal heatsink | Enables 6600 W surge handling without external heatsink by leveraging PCB copper as thermal path via anode mounting. |
| ISO 7637-2 compliance | Verified performance against load dump waveforms (e.g., Pulse 5a), critical for 12 V automotive power systems. |
| MSL Level 1 | Compatible with standard SMT reflow profiles up to 245 °C peak, eliminating moisture sensitivity concerns. |
Applications
| Automotive Load Dump Protection | Engine Control Unit (ECU) Power Input |
|---|---|
Use Scenario: Protecting vehicle electronics during alternator load dump events where battery voltage spikes to >35 V for up to 400 ms. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and ECU input to clamp transients before they reach DC/DC converters and microcontrollers. Use Value: Limits peak voltage to ≤29.2 V, preventing damage to 36 V-rated input stages while sustaining 6600 W surges per IEC 61000-4-5 and ISO 7637-2. |
Use Scenario: Safeguarding power inputs of engine control modules exposed to ignition noise, relay switching, and alternator ripple. IC Role / Device Role / Timing Role: Primary overvoltage suppression element on main 12 V supply line upstream of LDOs and PMICs. Use Value: Delivers 700 A single-pulse surge current handling and −55 °C to +175 °C operation, matching ECU environmental requirements. |
| Body Control Module (BCM) Power Rail | Advanced Driver Assistance Systems (ADAS) Camera Power |
Use Scenario: Securing low-voltage power distribution networks in door modules, lighting controllers, and HVAC systems. IC Role / Device Role / Timing Role: Standoff-clamp TVS on fused 12 V branches feeding CAN transceivers and sensor interfaces. Use Value: Low leakage (<10 μA at 175 °C) prevents battery drain; DO-218AB footprint enables compact layout near connectors. |
Use Scenario: Protecting image sensor and serializer power supplies in rear-view or surround-view cameras subject to cable-induced surges. IC Role / Device Role / Timing Role: Secondary protection stage after fuse and primary filter, placed immediately before camera module input. Use Value: 29.2 V clamping voltage aligns with typical 28 V absolute maximum ratings of image sensors and SerDes ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SM8S18AHM3 | No /I suffix; same electrical specs, but unspecified tape-and-reel orientation (anode direction not guaranteed). | Suitable for non-automotive production where anode alignment is not critical for automated placement. | Select SM8S18AHM3/I when anode-toward-sprocket-hole tape orientation is required for precise pick-and-place registration. |
| SM8S20AHM3/I | Higher VWM (20 V), VBR (22.2–24.5 V), and VC (32.4 V); identical package, thermal, and surge ratings. | Better suited for 24 V systems or designs requiring higher standoff margin before clamping activation. | Choose SM8S20AHM3/I if system nominal voltage exceeds 15 V or if design margin requires ≥20 V VWM. |
Compared with SM8S18AHM3/I, SM8S18AHM3 lacks guaranteed anode orientation in tape, while SM8S20AHM3/I shifts clamping onset upward-both retain DO-218AB packaging, AEC-Q101 qualification, and 6600 W surge capability, enabling flexible voltage-tier selection within the same footprint.
Availability
SM8S18AHM3/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, AEC-Q101 compliance, and high-temperature reliability.
Supply support for SM8S18AHM3/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 supplier of discrete semiconductors, specializing in diodes, MOSFETs, optoelectronics, and passive components with emphasis on automotive, industrial, and computing applications.
The SM8SxxA family is engineered specifically for high-energy transient suppression in harsh automotive environments, delivering AEC-Q101 reliability, 175 °C operation, and ISO 7637-2 compliance in the DO-218AB package.
FAQ
What is the clamping voltage of the SM8S18AHM3/I under maximum surge conditions?
The SM8S18AHM3/I exhibits a maximum clamping voltage (VC) of 29.2 V when subjected to its rated 6600 W peak pulse power with a 10/1000 μs waveform. This value is measured at the specified peak pulse current (IPPM) and defines the upper voltage limit imposed on protected circuitry during transient events. The SM8S18AHM3/I maintains this clamping performance across its full operating temperature range.
Is the SM8S18AHM3/I suitable for 24 V automotive systems?
The SM8S18AHM3/I is optimized for 12 V nominal systems, with a 18 V stand-off voltage (VWM) and 29.2 V clamping voltage. For 24 V systems, Vishay recommends higher-voltage variants such as SM8S24AHM3/I (VWM = 24 V) or SM8S28AHM3/I (VWM = 28 V) to maintain appropriate margin between nominal rail and clamping threshold. Using SM8S18AHM3/I in 24 V applications risks premature conduction and accelerated wear.
Does the SM8S18AHM3/I require a heatsink for 6600 W surge handling?
No external heatsink is required for the SM8S18AHM3/I to handle its rated 6600 W (10/1000 μs) surge, provided the anode (metal heatsink) is soldered to ≥10 cm² of 2 oz. copper on the PCB. Its RθJM of 0.35 °C/W enables effective heat transfer directly into the board. Thermal performance degrades significantly if the anode is isolated or minimally connected.
What does the "/I" suffix indicate in SM8S18AHM3/I?
The "/I" suffix in SM8S18AHM3/I specifies that the device is supplied in 13" diameter plastic tape and reel with anode oriented toward the sprocket hole-a critical detail for automated pick-and-place machines requiring consistent terminal alignment. This differs from SM8S18AHM3, which lacks orientation guarantee and may require vision-based placement verification.
How does the SM8S18AHM3/I meet AEC-Q101 requirements?
The SM8S18AHM3/I undergoes full AEC-Q101 stress testing-including temperature cycling, high-temperature operating life, and unbiased highly accelerated stress testing-to validate reliability for automotive under-hood use. Its construction uses passivated anisotropic rectifier technology and DO-218AB molding compound rated UL 94 V-0, both contributing to its qualification status as documented in Vishay's certification records.
SM8S18AHM3/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):
- 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
SM8S18AHM3/I FAQ
1.How can I place an order for SM8S18AHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S18AHM3/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 SM8S18AHM3/I reliable?
The price and inventory of SM8S18AHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S18AHM3/I is usually 5 days.
3.What payment methods are accepted for SM8S18AHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S18AHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S18AHM3/I?
SM8S18AHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S18AHM3/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 SM8S18AHM3/I?
For technical support, including SM8S18AHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S18AHM3/I requirements.
6.How does Aetrix verify that SM8S18AHM3/I is sourced from the original manufacturer or authorized distributors?
All SM8S18AHM3/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 SM8S18AHM3/I meets industry standards.
7.What is the process for return or replacement of SM8S18AHM3/I?
All SM8S18AHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S18AHM3/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 SM8S18AHM3/I part is unused and in its original packaging.
Return procedure for SM8S18AHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S18AHM3/I Tags
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