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STMicroelectronics SM15T18A
- Part No.:
- SM15T18A
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM15T18A.pdf
- Description:
- TVS DIODE 15.3VWM 32.5VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:3,242
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Product details
Overview
SM15T18A from STMicroelectronics is a unidirectional 1500 W transient voltage suppression diode in SMC package, designed for IEC 61000-4-2 ESD (30 kV air/contact) and IEC 61000-4-4 surge (4 kV level 4) protection. It features 18 V standoff voltage (VRM), 25.2 V clamping voltage at 1 A (VCL), 0.2 µA leakage at 25 °C, and operates up to 150 °C junction temperature. Used in AC/DC power supplies and industrial control inputs.
For engineers reviewing the SM15T18A datasheet, SM15T18A pinout, SM15T18A application, or SM15T18A equivalent, this page delivers verified electrical parameters, thermal derating behavior, SMC package layout, real-world clamping performance under 8/20 µs and 10/1000 µs transients, and direct alternatives with documented VBR and RD differences.
Technical Context
The SM15T18A employs planar silicon avalanche technology to achieve low dynamic resistance (RD = 0.106 Ω at 25 °C) and stable clamping across temperature (αT = 8.8 × 10⁻⁴ /°C). Its unidirectional configuration enables asymmetric surge handling-forward conduction during positive transients and reverse blocking up to VRM = 18 V.
Thermal performance is defined by junction-to-ambient thermal resistance (Rth(j-a) ≈ 100 °C/W on standard FR4 footprint), enabling sustained operation at Tj = 150 °C with peak pulse power up to 1250 W (10/1000 µs). Clamping voltage scales linearly with temperature per VCL(Tj) = VCL(25°C) × [1 + αT × (Tj − 25)].
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - Maximum continuous reverse working voltage before breakdown; defines minimum system operating margin. |
| Breakdown Voltage (VBR) | 15.3–18.9 V at 1 mA - Confirmed min/typ/max range ensures reliable triggering across production lot and temperature. |
| Clamping Voltage (VCL) | 25.2 V at 1 A (10/1000 µs) - Measured voltage across device during standardized surge; determines protected circuit's maximum stress level. |
| Peak Pulse Power (PPP) | 1500 W (10/1000 µs) - Sustained energy-handling capability at Tamb = 25 °C; derates to 1250 W at Tj = 150 °C. |
| Leakage Current (IRM) | 0.2 µA at VRM = 18 V, 25 °C - Ultra-low reverse current minimizes standby power loss in high-impedance sensing or battery-backed circuits. |
| Dynamic Resistance (RD) | 0.106 Ω - Low impedance during clamping reduces voltage overshoot and improves surge current sharing in parallel configurations. |
| Junction Temperature Range | −55 to +150 °C - Enables deployment in automotive engine compartments and industrial motor drives without derating. |
Pinout & Package
SM15T18A is housed in an SMC (DO-214AB) surface-mount package with two terminals: Cathode (K) and Anode (A). The package measures 7.75–8.15 mm × 5.55–6.25 mm × 2.45 mm max height, with matte tin-plated leads compliant with J-STD-002 and IPC7531 footprint standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Surge return path | Connected to ground or low-impedance reference; carries full transient current during clamping. |
| Cathode (K) | Protected line connection | Connected to signal/power line being protected; reverse-biased during normal operation, avalanches during overvoltage. |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61000-4-2 ESD robustness | 30 kV air and contact discharge - Eliminates need for external pre-filtering in industrial HMI and sensor interfaces. |
| Low temperature coefficient (αT) | 8.8 × 10⁻⁴ /°C - Ensures predictable VCL shift across −55 to +150 °C, critical for automotive and outdoor equipment. |
| High-temperature power rating | 1250 W at Tj = 150 °C - Supports compact PCB layouts where thermal dissipation is constrained by enclosure or adjacent components. |
| UL 497B certification | File QVGQ2.E136224 - Validates suitability for telecom and industrial data line protection per UL safety requirements. |
| ECOPACK® compliance | Meets RoHS and halogen-free standards - Enables global market access without material declaration overhead. |
Applications
| AC/DC Power Input Protection | Industrial PLC Digital Input |
|---|---|
Use Scenario: Protecting rectified AC mains input of switch-mode power supplies against lightning-induced surges and load dump transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between L/N lines and earth ground to clamp common-mode surges up to 4 kV (IEC 61000-4-4 level 4). Use Value: 25.2 V clamping limits stress on bridge rectifier and bulk capacitor; 0.2 µA leakage avoids unnecessary standby current drain. | Use Scenario: Shielding 24 V DC digital input channels in programmable logic controllers from field-wiring induced transients. IC Role / Device Role / Timing Role: Reverse-biased TVS connected between input terminal and chassis ground to suppress fast-rising EFT bursts. Use Value: 30 kV ESD immunity prevents false triggering or latch-up; SMC package allows automated placement alongside optocouplers and filtering resistors. |
| Motor Drive Control Signal Line | Smart Meter Communication Port |
Use Scenario: Safeguarding enable/disable and fault feedback signals routed between MCU and gate driver ICs in variable-frequency drives. IC Role / Device Role / Timing Role: Point-of-load TVS on isolated control lines to absorb coupling noise from high-di/dt power switching. Use Value: 0.106 Ω RD minimizes clamping delay and overshoot; 150 °C rating matches ambient near IGBT heatsinks. | Use Scenario: Protecting RS-485 or M-Bus communication ports in utility smart meters exposed to meter cabinet-level surges. IC Role / Device Role / Timing Role: Series-connected TVS on differential bus lines to maintain signal integrity while meeting IEC 61000-4-5 (1 kV) requirements. Use Value: 18 V VRM aligns with 24 V bus rails; low capacitance (<100 pF at 1 V) avoids signal edge degradation at 100 kbps+ data rates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18A (Bourns) | VBR = 19.0–21.1 V; VCL = 29.2 V @ 1 A; RD = 0.15 Ω; 600 W rating | Lower power handling and higher clamping reduce margin in high-energy surge environments | Select when cost sensitivity outweighs 1500 W requirement and board space permits larger SMB footprint |
| P6SMB18A (Littelfuse) | VBR = 18.0–20.0 V; VCL = 27.7 V @ 1 A; RD = 0.12 Ω; 600 W rating | Limited to 600 W peak power; not rated for 1250 W at 150 °C | Prefer for legacy designs using SMB package; verify thermal design if replacing SM15T18A in high-temperature zones |
Compared with SMBJ18A and P6SMB18A, SM15T18A delivers 2.5× higher peak power, lower clamping voltage, and validated 150 °C operation-making it suitable for next-generation industrial power systems where thermal headroom and surge margin are critical.
Availability
SM15T18A is available at Aetrix Electronics and suitable for AC/DC power input protection, industrial PLC digital input conditioning, and motor drive control signal line safeguarding requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SM15T18A 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, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.
The SM15T series belongs to ST's high-power TVS portfolio, engineered specifically for robust front-end surge protection in harsh electromagnetic environments-emphasizing low leakage, tight VBR tolerance, and guaranteed performance at 150 °C junction temperature.
FAQ
What is the maximum clamping voltage of SM15T18A under a 10/1000 µs surge?
The maximum clamping voltage (VCL) of SM15T18A is 25.2 V when subjected to a 1 A 10/1000 µs surge waveform at 25 °C. This value increases with junction temperature per the coefficient αT = 8.8 × 10⁻⁴ /°C, reaching approximately 27.5 V at Tj = 150 °C.
Is SM15T18A bidirectional or unidirectional?
SM15T18A is a unidirectional TVS diode, meaning it conducts only in reverse breakdown (cathode-to-anode) during overvoltage events and blocks forward current like a standard diode. Its bidirectional counterpart is SM15T18CA, which clamps in both polarities.
Does SM15T18A meet IEC 61000-4-5 surge immunity requirements?
SM15T18A is rated for IEC 61000-4-4 (EFT, 4 kV level 4) and IEC 61000-4-2 (ESD, 30 kV), but it is not certified to IEC 61000-4-5 (lightning surge), which requires higher energy handling (e.g., 1–2 kV line-to-ground). For IEC 61000-4-5 compliance, use in conjunction with GDTs or MOVs in coordinated protection stages.
What is the recommended PCB footprint for SM15T18A?
The recommended footprint follows IPC7531 and JEDEC MO-136 outlines: pad length 5.11 mm, pad width 3.14 mm, center-to-center spacing 8.19 mm, with 1.54 mm solder mask opening. Copper area ≥ 3 cm² per pad improves thermal dissipation and supports 1250 W derated power at 150 °C.
SM15T18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AB, SMC
- Series:
- SM15T, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 15.3V
- Voltage - Breakdown (Min):
- 17.1V
- Voltage - Clamping (Max) @ Ipp:
- 32.5V
- Current - Peak Pulse (10/1000µs):
- 308A (8/20µs)
- Power - Peak Pulse:
- 1500W (1.5kW)
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMC
SM15T18A FAQ
1.How can I place an order for SM15T18A through Aetrix?
Please submit a Request for Quotation (RFQ) for SM15T18A 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 SM15T18A reliable?
The price and inventory of SM15T18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM15T18A is usually 5 days.
3.What payment methods are accepted for SM15T18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM15T18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM15T18A?
SM15T18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM15T18A 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 SM15T18A?
For technical support, including SM15T18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM15T18A requirements.
6.How does Aetrix verify that SM15T18A is sourced from the original manufacturer or authorized distributors?
All SM15T18A 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 SM15T18A meets industry standards.
7.What is the process for return or replacement of SM15T18A?
All SM15T18A units undergo pre-shipment inspection (PSI). If there is an issue with SM15T18A, 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 SM15T18A part is unused and in its original packaging.
Return procedure for SM15T18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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