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STMicroelectronics SM6F18AY
- Part No.:
- SM6F18AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- SOD-128
- Datasheet:
-
SM6F18AY.pdf
- Description:
- TVS DIODE 18VWM 39.3VC SOD128FLT
- Quantity:
- Payment:
- Shipping:
Inventory:5,975
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Product details
Overview
SM6F18AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SOD128 Flat package, designed to clamp transient surges up to 39.3 A (8/20 µs) with a clamping voltage of 29.2 V and stand-off voltage of 18 V. It delivers 600 W peak pulse power (10/1000 µs), operates up to 175 °C junction temperature, and meets ISO 10605 ±30 kV ESD and ISO 7637-2 Pulse 1/2a/3a/3b requirements for 12 V battery systems.
For engineers reviewing the SM6F18AY datasheet, SM6F18AY pinout, SM6F18AY application, or SM6F18AY equivalent, this device is selected for robust front-end surge protection in automotive power line interfaces-especially where low leakage (0.2 µA at 25 °C), high-temperature stability, and IEC/ISO-compliant transient immunity are mandatory.
Technical Context
The SM6F18AY employs planar silicon technology to achieve low dynamic resistance (0.326 Ω at 25 °C, 10/1000 µs) and stable breakdown voltage (20–22.2 V) across temperature. Its unidirectional configuration enables asymmetric clamping for DC-biased lines such as battery feeds and LIN/CAN power rails.
It supports full automotive transients per ISO 7637-2: Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V), with verified clamping performance up to 175 °C junction temperature and ≤1 µA leakage at 85 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 18 V - Maximum continuous reverse operating voltage before significant leakage; defines minimum system operating margin. |
| Breakdown Voltage (VBR) | 20–22.2 V at 1 mA - Confirmed avalanche onset range; ensures reliable triggering before downstream IC damage. |
| Clamping Voltage (VCL) | 29.2 V at 39.3 A (8/20 µs) - Peak voltage seen by protected circuit during worst-case surge; critical for 30 V-rated load switch survival. |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - Sustained energy absorption capability under standard automotive test waveform. |
| Leakage Current (IRM) | 0.2 µA at 25 °C, 1 µA at 85 °C - Enables low-power always-on circuits (e.g., body control modules) without battery drain penalty. |
| Junction Temperature Range | −55 to +175 °C - Validated operation under hood conditions; supports placement near engine control units or power converters. |
| ESD Withstand | ±30 kV (IEC 61000-4-2, 150 pF/330 Ω) - Exceeds automotive level 4; eliminates need for secondary ESD protection on PCB. |
Pinout & Package
SOD128 Flat package: surface-mount, two-terminal, lead-free matte tin-plated leads, JEDEC-registered outline, IPC7531-compliant footprint. Dimensions: 4.7 mm × 2.4 mm × 1.0 mm (L × W × H), thermal pad optimized for FR4 PCB with ≥1 cm² copper area per lead.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Low-side connection to ground reference | Connected to chassis or local GND; forms return path for surge current during negative transients (Pulse 1, 3a). |
| Cathode (K) | High-side connection to protected line | Placed in series with 12 V supply rail; clamps positive overvoltage (Pulse 2a, 3b) by shunting to ground. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood use including temperature cycling, humidity bias, and mechanical shock per stress test plan. |
| High-temperature surge capability | Maintains 240 W (10/1000 µs) clamping performance at Tj = 175 °C - enables placement near heat sources without derating. |
| Low dynamic resistance | 0.326 Ω (25 °C, 10/1000 µs) - minimizes VCL rise under high-current pulses, improving protection margin for 24 V tolerant loads. |
| ESD robustness beyond ISO 10605 | Passes ±30 kV contact/air discharge (C = 330 pF, R = 330 Ω) - exceeds OEM requirements for infotainment and ADAS sensor interfaces. |
| Planar junction construction | Enables tight VBR tolerance and low leakage vs. traditional diffused junctions - critical for long-term reliability in sealed modules. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus Supply |
|---|---|
|
Use Scenario: 12 V battery feed to microcontroller power supply in gasoline/diesel engine compartments. IC Role / Device Role / Timing Role: Primary transient suppressor on main VBAT input, placed upstream of DC-DC converter and LDO regulators. Use Value: Clamps ISO 7637-2 Pulse 1 (−150 V) and Pulse 3a (−220 V) to ≤29.2 V, preventing latch-up or gate oxide rupture in 3.3 V/5 V logic supplies. |
Use Scenario: 12 V-to-12 V LIN transceiver power rail in door modules and seat controllers. IC Role / Device Role / Timing Role: Unidirectional clamping device protecting LIN physical layer ICs from load dump and inductive kickback. Use Value: Low 0.2 µA leakage preserves sleep-mode current budget; 175 °C rating allows direct mounting on high-temperature PCB zones near motors. |
| ADAS Camera Power Line | Electric Power Steering (EPS) Sensor Interface |
|
Use Scenario: 12 V power input to image sensor and ISP SoC in forward-facing camera modules. IC Role / Device Role / Timing Role: First-line defense against ESD events during assembly and roadside ESD exposure in vehicle exterior locations. Use Value: ±30 kV air/contact discharge immunity eliminates need for additional polymer TVS or RC filters, reducing BOM count and board space. |
Use Scenario: 12 V supply to torque and position sensors in EPS motor control assemblies. IC Role / Device Role / Timing Role: Surge protector on sensor VDD line, co-located with isolated CAN transceivers and analog front-ends. Use Value: Stable VBR and low αT (9.2 × 10⁻⁴/°C) ensure consistent clamping across −40 to +125 °C ambient, avoiding false trips or under-clamping. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Lower PPP (400 W), higher VCL (32.4 V at 24.4 A), SMC package (larger footprint, higher thermal resistance) | Not qualified to AEC-Q101; limited to non-safety-critical consumer or industrial use | Use only if cost sensitivity outweighs automotive qualification and thermal performance requirements. |
| TPSMD18A | Same PPP (600 W), lower VCL (27.7 V at 39.3 A), but higher IRM (1 µA at 25 °C) and no ISO 7637-2 Pulse 3b validation | Lacks documented Pulse 3b (+150 V) compliance; not recommended for battery rail protection in start-stop systems | Select when lower clamping voltage is prioritized and Pulse 3b immunity is not required by OEM specification. |
Compared with SMAJ18A and TPSMD18A, SM6F18AY uniquely combines AEC-Q101 qualification, validated ISO 7637-2 Pulse 3b immunity, and 0.2 µA leakage - making it the only choice for safety-critical 12 V power rail protection in modern automotive ECUs and ADAS systems.
Availability
SM6F18AY is available at Aetrix Electronics and suitable for automotive power line protection, ECU front-end surge suppression, and LIN/CAN bus power conditioning requiring stable component supply across extended temperature and lifecycle demands.
Supply support for SM6F18AY 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management solutions with vertical manufacturing and broad IP portfolio.
The SM6FxxAY series belongs to ST's automotive-grade TVS portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V battery-powered vehicle subsystems - emphasizing reliability, thermal resilience, and zero-defect field performance.
FAQ
What is the maximum clamping voltage of SM6F18AY under ISO 7637-2 Pulse 3b?
The SM6F18AY clamps to ≤29.2 V at 39.3 A (8/20 µs), and its validated performance under ISO 7637-2 Pulse 3b (+150 V) is confirmed in the DS13062 datasheet Figure 15. This clamping level protects 30 V-rated power switches and linear regulators without overstress.
Does SM6F18AY require a heatsink for 175 °C operation?
No external heatsink is required. The SOD128 Flat package achieves Rth(j-a) ≈ 120 °C/W on standard FR4 with 1 cm² copper per lead (per Figure 11), and its 240 W surge capability at 175 °C is specified under single-pulse conditions with no forced convection.
Can SM6F18AY be used in bidirectional configurations?
No - SM6F18AY is strictly unidirectional. Its cathode-anode polarity is fixed for DC-biased lines. For bidirectional protection (e.g., data lines), ST recommends the SMBJ18CA or similar symmetrical TVS devices from the same family.
How does the 9.2 × 10⁻⁴/°C voltage temperature coefficient affect system design?
This αT value means VBR increases by ~0.17 V per 10 °C rise above 25 °C. At 125 °C, VBR reaches ~23.5 V - still safely below the 30 V absolute maximum rating of common automotive power ICs, ensuring margin retention across full operating range.
SM6F18AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- SOD-128
- Series:
- SM6F
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V (Max)
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 39.3V
- Current - Peak Pulse (10/1000µs):
- 102A (8/20µs)
- Power - Peak Pulse:
- 600W
- 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:
- SOD128Flat
SM6F18AY FAQ
1.How can I place an order for SM6F18AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM6F18AY 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 SM6F18AY reliable?
The price and inventory of SM6F18AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM6F18AY is usually 5 days.
3.What payment methods are accepted for SM6F18AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM6F18AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM6F18AY?
SM6F18AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM6F18AY 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 SM6F18AY?
For technical support, including SM6F18AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM6F18AY requirements.
6.How does Aetrix verify that SM6F18AY is sourced from the original manufacturer or authorized distributors?
All SM6F18AY 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 SM6F18AY meets industry standards.
7.What is the process for return or replacement of SM6F18AY?
All SM6F18AY units undergo pre-shipment inspection (PSI). If there is an issue with SM6F18AY, 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 SM6F18AY part is unused and in its original packaging.
Return procedure for SM6F18AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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