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Vishay General Semiconductor - Diodes Division SM8S18CAHM3/I
- Part No.:
- SM8S18CAHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
SM8S18CAHM3/I.pdf
- Description:
- 6600 W BI-DIRECTIONAL TVS IS DO-
- Quantity:
- Payment:
- Shipping:
Inventory:1,410
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Product details
Overview
SM8S18CAHM3/I from Vishay General Semiconductor is a bidirectional surface-mount PAR® transient voltage suppressor (TVS) designed for automotive load dump protection. It features a 18 V stand-off voltage (VWM), 20.0–22.1 V breakdown voltage (VBR), 29.2 V maximum clamping voltage at 226 A peak pulse current, and 6600 W peak pulse power (10/1000 μs). Its DO-218AC package supports AEC-Q101 qualification and 175 °C junction operation.
For engineers reviewing the SM8S18CAHM3/I datasheet, SM8S18CAHM3/I pinout, SM8S18CAHM3/I application, or SM8S18CAHM3/I equivalent, this device is selected for high-reliability 12 V automotive power rail protection where ISO 7637-2 surge immunity, low leakage (<10 μA at VWM), and MSL Level 1 reflow compatibility are critical design requirements.
Technical Context
This TVS diode operates as a bidirectional clamping device with no polarity marking, enabling symmetric transient suppression on DC rails. Its silicon avalanche structure delivers precise VBR tolerance (±5 %), stable clamping under repetitive surges, and thermal robustness up to TJ = 175 °C - validated per AEC-Q101 stress tests including temperature cycling and high-temperature operating life.
The DO-218AC package integrates a metal heatsink terminal (Lead 2) for low RθJM (0.35 °C/W), enabling efficient heat transfer during high-energy transients. It meets JESD 201 Class 2 whisker resistance and UL 94 V-0 flammability, supporting automated SMT assembly with 245 °C peak reflow profile compliance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18.0 V - Maximum continuous reverse operating voltage before clamping begins; sets minimum system overvoltage threshold for 12 V automotive rails. |
| VBR (min–max) | 20.0–22.1 V at 5 mA - Tight ±5 % tolerance ensures predictable turn-on across production lots and temperature range. |
| VC @ IPPM | 29.2 V at 226 A (10/1000 μs) - Clamping voltage defines worst-case rail overshoot during load dump; enables downstream IC survival per ISO 16750-2. |
| PPPM (10/1000 μs) | 6600 W - Peak transient energy handling capacity; supports full ISO 7637-2 Pulse 5a (load dump) without degradation. |
| ID @ VWM | <10 μA at 25 °C - Low leakage preserves battery drain budget in always-on vehicle modules (e.g., body control units). |
| TJ max | 175 °C - Enables placement near hot engine compartments or power electronics without derating. |
| Package | DO-218AC - Metal heatsink lead (Lead 2) provides direct thermal path to PCB copper; footprint complies with IPC-7351. |
Pinout & Package
DO-218AC package with two terminals: Lead 1 (anode/cathode-indifferent) and Lead 2 (metal heatsink tab). No polarity band; bidirectional operation confirmed. Mounting pad layout follows IPC-7351 standard with 0.197" × 0.185" body outline and 0.098" heatsink pad width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Lead 1 | Anode/Cathode (bidirectional) | Connects to protected line; identical electrical behavior in either direction; no orientation required during placement. |
| Lead 2 | Heatsink / Cathode (thermal path) | Primary thermal interface to PCB copper; must be soldered to ≥2 oz. copper pour for RθJM = 0.35 °C/W performance. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive underhood use via temperature cycling, HTRB, and ESD testing - eliminates need for additional qualification by Tier 1 suppliers. |
| MSL Level 1, 245 °C peak | Supports standard lead-free reflow without moisture sensitivity concerns; no baking required prior to assembly. |
| ISO 7637-2 & ISO 16750-2 compliant | Meets Pulse 5a (load dump) and Pulse 1/2a (inductive switching) test criteria - reduces need for external filtering components. |
| Halogen-free, RoHS-compliant (M3) | Meets global environmental regulations and OEM material declarations (e.g., VW 80101); no brominated flame retardants. |
| Junction-to-mount thermal resistance | RθJM = 0.35 °C/W - enables >80 % of rated PPPM power dissipation even at 100 °C ambient when mounted on 2 oz. copper. |
Applications
| Automotive Load Dump Protection | Engine Control Unit (ECU) Power Input |
|---|---|
Use Scenario: Suppresses 12 V battery line transients caused by alternator field collapse during ignition-off events (ISO 7637-2 Pulse 5a). IC Role / Device Role / Timing Role: Clamps rail voltage to ≤29.2 V within nanoseconds, preventing overvoltage damage to microcontrollers and analog front-ends. Use Value: Eliminates need for upstream LC filters or secondary TVS stages; maintains system uptime during repeated load dump events. | Use Scenario: Protects 5 V/3.3 V regulator inputs in engine control modules exposed to cranking dips and relay-switching spikes. IC Role / Device Role / Timing Role: Acts as primary overvoltage clamp ahead of LDOs, ensuring input stays below absolute maximum ratings during transients. Use Value: Enables single-stage protection architecture with <10 μA leakage - critical for low-power sleep modes in modern ECUs. |
| Body Control Module (BCM) Power Rail | ADAS Camera Power Supply |
Use Scenario: Shields BCM power inputs from inductive kickback generated by door lock actuators, window motors, and HVAC relays. IC Role / Device Role / Timing Role: Provides bidirectional clamping on 12 V supply lines shared across multiple loads, with no polarity constraints during layout. Use Value: Reduces BOM count by replacing dual unidirectional TVS arrays; simplifies PCB routing with symmetric terminal geometry. | Use Scenario: Safeguards 12 V input to image sensor power management ICs in rear-view and surround-view cameras. IC Role / Device Role / Timing Role: Limits transient overshoot to <29.2 V during hot-swap events or cable ESD, preserving pixel integrity and ADC reference stability. Use Value: Maintains <10 μA leakage at 18 V - avoids dark current drift in CMOS image sensors during long exposure cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CA | Lower PPPM (400 W vs. 6600 W); DO-214AC package; no AEC-Q101 qualification. | Suitable for consumer-grade 12 V supplies; insufficient for automotive load dump per ISO 7637-2. | Select SMAJ18CA only for cost-sensitive non-automotive designs with sub-100 A surge requirements. |
| TPSMD18CA | Same DO-218AC package; 6600 W PPPM; but VBR = 20.0–22.2 V and VC = 29.5 V - functionally identical clamping performance. | Also AEC-Q101 qualified; differs only in manufacturer-specific process and screening flow. | TPSMD18CA offers drop-in replacement capability with identical electrical and mechanical specs; verify sourcing continuity. |
Compared with SM8S18CAHM3/I, SMAJ18CA lacks automotive qualification and surge capacity, limiting use to industrial controls; TPSMD18CA matches all key parameters and package, enabling direct substitution where second-source assurance is required.
Availability
SM8S18CAHM3/I is available at Aetrix Electronics and suitable for automotive power rail protection, engine control unit (ECU) input conditioning, and ADAS camera power supply applications requiring stable component supply across multi-year production cycles.
Supply support for SM8S18CAHM3/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 diodes, rectifiers, and protection devices with emphasis on automotive and industrial reliability.
The SM8S family is engineered specifically for high-energy automotive transient suppression, targeting ISO 7637-2 compliance and under-hood thermal resilience up to 175 °C junction temperature.
FAQ
What is the maximum clamping voltage of SM8S18CAHM3/I at its rated peak pulse current?
The SM8S18CAHM3/I has a maximum clamping voltage (VC) of 29.2 V at its rated peak pulse current (IPPM) of 226 A under the 10/1000 μs waveform. This value is measured per Figure 4 in the Vishay datasheet (Doc. #98229) and defines the upper voltage limit imposed on the protected circuit during worst-case transients.
Is SM8S18CAHM3/I qualified for automotive applications?
Yes, SM8S18CAHM3/I is AEC-Q101 qualified and explicitly designed for automotive use. It meets ISO 7637-2 (load dump) and ISO 16750-2 surge standards, operates up to 175 °C junction temperature, and passes JESD 201 Class 2 whisker testing - all documented in Vishay's official qualification report for the SM8S series.
What does the 'HM3' suffix indicate in SM8S18CAHM3/I?
The 'HM3' suffix in SM8S18CAHM3/I denotes halogen-free, RoHS-compliant construction (M3) and AEC-Q101 qualification (H). The 'I' indicates packaging in 13" plastic tape and reel with anode toward sprocket hole - a standard delivery format verified in Vishay's ordering information table (Doc. #98229, page 3).
Can SM8S18CAHM3/I be used in bidirectional signal line protection?
No, SM8S18CAHM3/I is optimized for high-power DC power rail protection (e.g., 12 V battery lines), not low-capacitance signal lines. Its junction capacitance is not specified in the datasheet, and its 29.2 V clamping voltage exceeds typical signal voltage levels; use dedicated low-C TVS arrays like the USBxx series for data line protection.
What is the thermal resistance from junction to mount (RθJM) for SM8S18CAHM3/I?
The SM8S18CAHM3/I has a typical junction-to-mount thermal resistance (RθJM) of 0.35 °C/W, measured per JEDEC 51-14 using the Transient Dual Interface Method. This low value is enabled by the DO-218AC metal heatsink terminal (Lead 2) and requires soldering to a ≥2 oz. copper thermal pad for full benefit.
SM8S18CAHM3/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:
- -
- Bidirectional Channels:
- 1
- 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-218AB
SM8S18CAHM3/I FAQ
1.How can I place an order for SM8S18CAHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S18CAHM3/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 SM8S18CAHM3/I reliable?
The price and inventory of SM8S18CAHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S18CAHM3/I is usually 5 days.
3.What payment methods are accepted for SM8S18CAHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S18CAHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S18CAHM3/I?
SM8S18CAHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S18CAHM3/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 SM8S18CAHM3/I?
For technical support, including SM8S18CAHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S18CAHM3/I requirements.
6.How does Aetrix verify that SM8S18CAHM3/I is sourced from the original manufacturer or authorized distributors?
All SM8S18CAHM3/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 SM8S18CAHM3/I meets industry standards.
7.What is the process for return or replacement of SM8S18CAHM3/I?
All SM8S18CAHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S18CAHM3/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 SM8S18CAHM3/I part is unused and in its original packaging.
Return procedure for SM8S18CAHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S18CAHM3/I Tags
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