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STMicroelectronics SM30T18AY
- Part No.:
- SM30T18AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM30T18AY.pdf
- Description:
- TVS DIODE 15VWM 24.4VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:3,296
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Product details
Overview
SM30T18AY from STMicroelectronics is a unidirectional 18 V standoff automotive TVS diode in SMC package, rated for 3000 W (10/1000 µs) peak pulse power, 24.4 V clamping voltage at 123 A surge current, and 0.2 µA leakage at 25 °C - designed to protect CAN, LIN, and sensor interfaces in 12 V vehicle systems against ISO 7637-2 pulses and ±30 kV ESD per ISO 10605.
For engineers reviewing the SM30T18AY datasheet, SM30T18AY pinout, SM30T18AY application, or SM30T18AY equivalent, this device delivers validated AEC-Q101 qualification, 175 °C junction temperature operation, JEDEC-registered SMC footprint compatibility, and precise clamping performance critical for automotive power line and data bus transient suppression.
Technical Context
The SM30T18AY employs planar silicon avalanche technology optimized for low leakage (0.2 µA at VRM = 18 V) and high thermal stability up to Tj = 175 °C. Its dynamic resistance of 15.1 mΩ enables tight clamping control under fast transients like ISO 7637-2 Pulse 3b (+150 V).
It meets stringent automotive immunity standards: IEC 61000-4-4 Level 4 (4 kV), ISO 10605 (±30 kV air/contact discharge), and ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) - all verified with 12 V battery reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - maximum continuous reverse operating voltage before breakdown; sets minimum system operating margin for 12 V automotive rails. |
| Breakdown Voltage (VBR) | 16.7–18.5 V at 1 mA - ensures reliable triggering above normal rail noise while avoiding false conduction during load dump overshoot. |
| Clamping Voltage (VCL) | 24.4 V at 123 A (10/1000 µs) - limits downstream IC stress to safe levels during ISO 7637-2 Pulse 1 and Pulse 3a events. |
| Peak Pulse Power | 3000 W (10/1000 µs), up to 926 W (8/20 µs) - sustains high-energy surges without thermal runaway in engine bay environments. |
| Leakage Current (IRM) | 0.2 µA at 18 V, 25 °C - minimizes standby power loss in always-on modules such as body control units and telematics. |
| Junction Temperature Range | −55 °C to +175 °C - supports placement near heat sources (e.g., ECUs, power converters) without derating. |
| AEC-Q101 Qualification | Qualified - validates reliability for automotive safety-critical applications including ADAS sensor power rails and infotainment USB ports. |
Pinout & Package
SM30T18AY is housed in a JEDEC-registered SMC (DO-214AB) surface-mount package with matte tin-plated leads, compatible with IPC-7531 footprint and reflow profiles per J-STD-020 MSL Level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Marked Band) | Surge current sink node | Connected to protected line (e.g., CAN_H); conducts transient energy to ground when VLINE exceeds VBR. |
| Anode | Reference / ground return | Typically tied to chassis or signal ground; completes low-inductance path for clamped current during ESD or load dump events. |
Key Features
| Feature | Design Value |
|---|---|
| Low clamping ratio (VCL/VBR) | 1.38 - reduces voltage overshoot on protected lines, enabling use with 24 V tolerant receivers in mixed-voltage domains. |
| High surge current capability | 123 A (10/1000 µs) - withstands repetitive ISO 7637-2 Pulse 1 events without parameter shift or degradation. |
| Ultra-low leakage | 0.2 µA at 25 °C - preserves battery life in always-on vehicle networks (e.g., LIN gateway sleep mode). |
| Thermal robustness | 175 °C max Tj - eliminates need for thermal derating in under-hood ECUs operating at ambient >125 °C. |
| ESD immunity | ±30 kV contact/air per ISO 10605 - protects USB-C, SD card, and display interface connectors from human-body-model discharges. |
Applications
| Automotive CAN Bus Protection | Body Control Module Power Input |
|---|---|
Use Scenario: Transient suppression on CAN_H/CAN_L lines in powertrain and chassis ECUs exposed to alternator load dump and inductive switching noise. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between CAN transceiver pins and connector, triggered within nanoseconds to limit VCL ≤ 24.4 V. Use Value: Prevents permanent damage to ISO 11898-2 compliant transceivers during ISO 7637-2 Pulse 3b (+150 V) and ESD events without affecting signal integrity. |
Use Scenario: Input protection for 12 V supply rail of BCMs handling door lock, lighting, and HVAC control functions. IC Role / Device Role / Timing Role: Primary overvoltage clamp on main power input, absorbing Pulse 1 (−150 V) and Pulse 2a (+112 V) energy before LDO regulators. Use Value: Enables single-stage protection without series resistors or RC filters, reducing BOM count and PCB area while maintaining <1 µA quiescent current. |
| ADAS Camera Power Rail | Infotainment USB Port ESD Guard |
Use Scenario: 12 V camera module power input in forward-facing radar/camera fusion units mounted behind windshield. IC Role / Device Role / Timing Role: Fast-response TVS placed directly at connector entry point, clamping ISO 7637-2 Pulse 3a (−220 V) within 1 ns. Use Value: Maintains uninterrupted video streaming by limiting rail collapse to <24.4 V, preventing brownout resets in image signal processors. |
Use Scenario: ESD protection for USB 2.0 D+/D− and VBUS lines in head unit and rear-seat entertainment systems. IC Role / Device Role / Timing Role: Bidirectional-capable unidirectional device used in dual-rail configuration (SM30T18AY + SM30T18CAY) for full differential and common-mode ESD suppression. Use Value: Passes ±30 kV IEC 61000-4-2 testing without latch-up or parameter drift, ensuring long-term USB port reliability across vehicle lifecycle. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar automotive TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ18A | Same SMC package, but higher VCL = 29.2 V at 103 A (10/1000 µs); 10% higher leakage (2 µA). | Marginally lower surge current rating; less suitable for high-repetition ISO 7637-2 Pulse 1 scenarios in engine control units. | Select when cost sensitivity outweighs clamping precision; verify thermal design margin due to higher VCL-induced power dissipation. |
| Vishay SMA6J18A | Lower peak power (600 W vs. 3000 W); VCL = 27.7 V at 21.7 A - insufficient for ISO 7637-2 Pulse 1 compliance. | Rated only for IEC 61000-4-2 ESD, not full automotive surge standards; unsuitable for power line protection. | Use only for non-critical signal-line ESD guard where ISO 7637-2 immunity is not required - e.g., interior button interfaces. |
Compared with SMAJ18A and SMA6J18A, SM30T18AY provides superior clamping accuracy (24.4 V), 5× higher surge current capacity, and AEC-Q101 validation - making it the only choice for functional-safety-relevant power rail protection in ASIL-B systems.
Availability
SM30T18AY is available at Aetrix Electronics and suitable for automotive electronic control units, ADAS camera modules, and infotainment system power inputs requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SM30T18AY 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 over 40 years of analog and protection device expertise.
The SM30Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically for robust transient immunity in harsh vehicle environments - targeting ISO 7637-2, ISO 10605, and ISO 16750-2 compliance without external circuitry.
FAQ
What is the maximum clamping voltage of SM30T18AY under ISO 7637-2 Pulse 1 conditions?
The SM30T18AY clamps to 24.4 V at 123 A for a 10/1000 µs waveform, which directly covers ISO 7637-2 Pulse 1 (−150 V, 50 Ω source impedance). Measured VCL remains stable across −55 °C to +150 °C junction temperatures, with no degradation after 1000 surge cycles.
Can SM30T18AY be used in bidirectional signal lines like CAN or LIN?
SM30T18AY is unidirectional and must be paired with a second device (e.g., SM30T18CAY) for full bidirectional protection on differential buses. For CAN, it is typically placed on the CAN_H line with cathode to the line and anode to ground, while a matching bidirectional part handles common-mode transients.
How does SM30T18AY's leakage current compare to standard industrial TVS diodes?
At 18 V and 25 °C, SM30T18AY exhibits only 0.2 µA leakage - 10× lower than typical industrial-grade SMC TVS diodes (e.g., 2–5 µA). This enables direct integration into always-on automotive subsystems without compromising battery drain budgets.
Is SM30T18AY compatible with lead-free reflow soldering processes?
Yes - SM30T18AY uses matte tin-plated leads and conforms to J-STD-020 MSL Level 1. It supports peak reflow temperatures up to 245 °C for 20–30 seconds, matching standard Pb-free SAC305 profiles without delamination or parametric shift.
SM30T18AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AB, SMC
- Series:
- SM30TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 15V
- Voltage - Breakdown (Min):
- 16.7V
- Voltage - Clamping (Max) @ Ipp:
- 24.4V
- Current - Peak Pulse (10/1000µs):
- 123A
- Power - Peak Pulse:
- 3000W (3kW)
- 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:
- SMC
SM30T18AY FAQ
1.How can I place an order for SM30T18AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM30T18AY 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 SM30T18AY reliable?
The price and inventory of SM30T18AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM30T18AY is usually 5 days.
3.What payment methods are accepted for SM30T18AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM30T18AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM30T18AY?
SM30T18AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM30T18AY 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 SM30T18AY?
For technical support, including SM30T18AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM30T18AY requirements.
6.How does Aetrix verify that SM30T18AY is sourced from the original manufacturer or authorized distributors?
All SM30T18AY 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 SM30T18AY meets industry standards.
7.What is the process for return or replacement of SM30T18AY?
All SM30T18AY units undergo pre-shipment inspection (PSI). If there is an issue with SM30T18AY, 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 SM30T18AY part is unused and in its original packaging.
Return procedure for SM30T18AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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