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STMicroelectronics SM30T18CAY
- Part No.:
- SM30T18CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM30T18CAY.pdf
- Description:
- TVS DIODE 15VWM 24.4VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:5,107
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Product details
Overview
SM30T18CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection and ISO 10605 ESD immunity in 12 V/24 V vehicle systems. It delivers 3000 W peak pulse power (10/1000 µs), clamps at 24.4 V (max) under 123 A surge, and maintains ≤0.2 µA leakage at 25 °C with 175 °C max junction temperature.
For engineers reviewing the SM30T18CAY datasheet, SM30T18CAY pinout, SM30T18CAY application, or SM30T18CAY equivalent, this device supports high-reliability automotive power line protection where low dynamic resistance (15.1 mΩ), precise clamping voltage stability across temperature, and AEC-Q101 qualification are critical selection criteria.
Technical Context
This bidirectional TVS diode uses planar silicon technology to achieve low leakage current and high thermal robustness up to 175 °C junction temperature. Its symmetrical breakdown behavior enables protection against both positive and negative transients without polarity constraints.
The device complies with ISO 7637-2 (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −220 V; Pulse 3b: +150 V) and exceeds IEC 61000-4-2 Level 4 ESD (±30 kV air/contact discharge, C = 150 pF/R = 330 Ω). Dynamic resistance of 15.1 mΩ ensures minimal voltage overshoot during fast 8/20 µs surges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power (10/1000 µs) | 3000 W - sustains automotive load dump and switching transients without failure |
| Clamping Voltage (IPP = 123 A) | 24.4 V max - limits downstream IC voltage stress during ISO 7637-2 Pulse 1 and 3a events |
| Breakdown Voltage (VBR) | 16.7–18.5 V - tight 10% tolerance ensures predictable turn-on before protected circuit damage |
| Leakage Current (VRM = 15 V) | ≤0.2 µA at 25 °C - negligible standby power loss in always-on automotive modules |
| Dynamic Resistance (RD) | 15.1 mΩ - minimizes clamping voltage rise under high di/dt transients (e.g., 8/20 µs) |
| Junction Temperature Range | −55 °C to +175 °C - supports under-hood placement in modern engine control units |
| AEC-Q101 Qualified | Validated for automotive reliability including temperature cycling, HTRB, and ESD stress |
Pinout & Package
SM30T18CAY is housed in a JEDEC-registered SMC (DO-214AB) surface-mount package with matte tin-plated leads and IPC-7531-compliant footprint. The bidirectional configuration has no anode/cathode distinction - both terminals function identically as symmetrical surge paths.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Surge input terminal (bidirectional) | Accepts positive or negative transient energy; identical electrical behavior to Cathode |
| Cathode (K) | Surge input terminal (bidirectional) | Accepts positive or negative transient energy; identical electrical behavior to Anode |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional surge handling | Enables single-device protection of AC-coupled or floating signal/power lines without polarity concerns |
| Low dynamic resistance (15.1 mΩ) | Reduces clamping voltage overshoot during fast-rising 8/20 µs transients common in ISO 7637-2 Pulse 2a/3b |
| AEC-Q101 qualification | Validates long-term reliability in automotive environments including thermal cycling and humidity exposure |
| 175 °C max operating junction temperature | Supports mounting near heat sources (e.g., power converters) without derating or thermal shutdown |
| ≤0.2 µA leakage at 25 °C | Preserves battery life in always-on vehicle networks (e.g., CAN FD gateways, body controllers) |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus |
|---|---|
|
Use Scenario: Protects 12 V supply rail of gasoline/diesel ECUs against alternator load dump and inductive switching spikes. IC Role / Device Role / Timing Role: Primary overvoltage clamp on main power entry point; responds within nanoseconds to transients exceeding 150 V. Use Value: Prevents latch-up or permanent damage to MCU, CAN transceivers, and analog front-ends during ISO 7637-2 Pulse 5b events. |
Use Scenario: Shields LIN physical layer transceivers from ESD and coupled noise on vehicle body harnesses. IC Role / Device Role / Timing Role: Bidirectional shunt protector on LIN bus line; clamps ±30 kV contact discharge per ISO 10605. Use Value: Maintains LIN communication integrity without signal distortion due to low capacitance (<100 pF at 1 V) and symmetrical response. |
| ADAS Camera Power Supply | Electric Power Steering (EPS) Motor Driver |
|
Use Scenario: Guards 5 V/3.3 V camera module power rails against reverse battery connection and jump-start surges. IC Role / Device Role / Timing Role: Secondary clamping stage after primary DC-DC converter; handles residual transients passing through filter inductors. Use Value: Ensures uninterrupted image capture by limiting voltage to <25 V during 100 ms load dump pulses (ISO 16750-2 Test B). |
Use Scenario: Protects H-bridge gate drivers and current sense amplifiers from motor back-EMF and PWM switching noise. IC Role / Device Role / Timing Role: High-energy transient suppressor on motor phase outputs and supply inputs; rated for 40 kW (8/20 µs). Use Value: Eliminates false triggering of overcurrent protection and prevents MOSFET avalanche failure during rapid direction reversal. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CA | Lower peak power (400 W), higher clamping voltage (32.4 V @ 12.3 A), SMC package but not AEC-Q101 qualified | Limited to non-automotive industrial or consumer applications with less stringent surge requirements | Select only if cost sensitivity outweighs automotive compliance and 3000 W capability |
| SMBJ18CA | Same SMC package, AEC-Q101 qualified, but lower peak power (600 W) and higher clamping (29.2 V @ 20.5 A) | Suitable for lower-energy CAN/LIN nodes but insufficient for main power rail protection per ISO 7637-2 Pulse 1/3a | Use where space-constrained PCBs require SMC footprint but system-level surge energy is below 1 kV |
Compared with SMAJ18CA and SMBJ18CA, SM30T18CAY provides 5× higher surge energy handling, tighter clamping voltage, and full automotive qualification-making it the only choice for main power rail protection in modern ECUs and ADAS systems requiring ISO 7637-2 compliance.
Availability
SM30T18CAY is available at Aetrix Electronics and suitable for automotive engine control units, body control modules, ADAS camera power supplies, and electric power steering systems requiring stable component supply with full AEC-Q101 traceability and long-lifecycle support.
Supply support for SM30T18CAY 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 capabilities and broad IP portfolio.
The SM30Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically for robust transient suppression in harsh vehicle environments-including under-hood power distribution, infotainment, and safety-critical ADAS subsystems.
FAQ
Is SM30T18CAY unidirectional or bidirectional?
SM30T18CAY is a bidirectional TVS diode, indicated by the "C" in its part number suffix. It provides symmetrical clamping for both positive and negative transients, making it ideal for protecting AC-coupled lines like LIN, CAN, or floating power rails without polarity constraints.
What is the maximum clamping voltage at 123 A surge current?
The maximum clamping voltage (VCL) for SM30T18CAY at 123 A (10/1000 µs waveform) is 24.4 V, measured at Tamb = 25 °C. This value increases slightly with junction temperature due to the αT coefficient of 10 × 10−4/°C, reaching ~25.5 V at 125 °C junction.
Does SM30T18CAY meet ISO 7637-2 Pulse 5b (load dump) requirements?
Yes - SM30T18CAY is validated for ISO 7637-2 Pulse 5b (load dump) with Us = 87 V and tp = 150–400 ms, as confirmed in Figures 18–22 of DS8599. Its 3000 W rating and low dynamic resistance enable reliable energy absorption without thermal runaway in 12 V battery systems.
Can SM30T18CAY replace SM30T18AY in a design?
No - SM30T18AY is unidirectional and intended for DC-biased lines (e.g., 12 V supply to MCU), while SM30T18CAY is bidirectional and suited for AC or floating signals. Substitution requires verifying circuit topology, bias conditions, and transient polarity; mixing types may result in incomplete protection or forward conduction failure.
SM30T18CAY 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:
- -
- Bidirectional Channels:
- 1
- 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
SM30T18CAY FAQ
1.How can I place an order for SM30T18CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM30T18CAY 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 SM30T18CAY reliable?
The price and inventory of SM30T18CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM30T18CAY is usually 5 days.
3.What payment methods are accepted for SM30T18CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM30T18CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM30T18CAY?
SM30T18CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM30T18CAY 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 SM30T18CAY?
For technical support, including SM30T18CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM30T18CAY requirements.
6.How does Aetrix verify that SM30T18CAY is sourced from the original manufacturer or authorized distributors?
All SM30T18CAY 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 SM30T18CAY meets industry standards.
7.What is the process for return or replacement of SM30T18CAY?
All SM30T18CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM30T18CAY, 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 SM30T18CAY part is unused and in its original packaging.
Return procedure for SM30T18CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM30T18CAY Tags
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