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STMicroelectronics SM15T18CA
- Part No.:
- SM15T18CA
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM15T18CA.pdf
- Description:
- TVS DIODE 15.3VWM 32.5VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:2,034
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Product details
Overview
SM15T18CA from STMicroelectronics is a bidirectional transient voltage suppression (TVS) diode designed for high-energy ESD and surge protection in power and signal lines. It features a 18 V standoff voltage (VRM), 25.2 V clamping voltage at 1 A (VCL), 32.5 A peak pulse current (IPP), and 1500 W peak pulse power (10/1000 µs) at 25 °C - deployed in industrial power supplies, telecom interfaces, and automotive body electronics.
For engineers reviewing the SM15T18CA datasheet, SM15T18CA pinout, SM15T18CA application, or SM15T18CA equivalent, key selection criteria include bidirectional clamping behavior, low leakage (0.2 µA at 25 °C), high junction temperature rating (150 °C), and SMC package compatibility with IPC7531 footprints and JEDEC-standard reflow profiles.
Technical Context
The SM15T18CA uses planar silicon avalanche technology to deliver precise, repeatable clamping during fast transients such as IEC 61000-4-2 ESD (±30 kV contact/air) and IEC 61000-4-4 EFT (4 kV level 4). Its bidirectional structure enables symmetrical protection on AC-coupled or floating lines without polarity constraints.
Clamping performance is defined by dynamic resistance (RD = 0.044 Ω at 25 °C), temperature coefficient αT = 8.8 × 10⁻⁴ /°C, and thermal impedance optimized for FR4 PCBs with recommended copper area. Junction capacitance remains below 100 pF at VR = 0 V, supporting high-speed data line integration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - maximum continuous reverse operating voltage before breakdown; defines minimum system operating margin. |
| Breakdown Voltage (VBR) | 15.3–18.9 V at 1 mA - ensures reliable triggering above normal operating voltage while avoiding false trips. |
| Clamping Voltage (VCL) | 25.2 V at 1 A (10/1000 µs) - limits downstream voltage stress to safe levels during surge events. |
| Peak Pulse Current (IPP) | 32.5 A (10/1000 µs) - supports robust protection against common industrial surges per IEC 61000-4-4. |
| Leakage Current (IRM) | 0.2 µA at VRM = 18 V and 25 °C - minimizes standby power loss and avoids interference in high-impedance sensing circuits. |
| Junction Temperature Range | −55 °C to +150 °C - enables deployment in under-hood automotive, industrial motor drives, and outdoor telecom enclosures. |
| Package | SMC (DO-214AB) - surface-mount outline compliant with IPC7531 and JEDEC MO-136AA; 7.75–8.15 mm width, 5.55–6.25 mm length. |
Pinout & Package
SM15T18CA is housed in an SMC (DO-214AB) plastic package with two terminals: Cathode (K) and Anode (A), arranged in a symmetrical bidirectional configuration. The device has no polarity marking distinction - both terminals function identically under reverse or forward surge conditions.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Surge current entry point (bidirectional) | Accepts transient energy from either direction; connects to protected line without polarity dependency. |
| Cathode (K) | Surge current return path (bidirectional) | Completes low-impedance path to ground or reference rail during clamping; identical functional role to Anode. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping architecture | Enables single-device protection of AC lines, differential buses (e.g., RS-485), and floating inputs without external polarity management. |
| Low dynamic resistance (RD = 0.044 Ω) | Reduces clamping voltage rise under high-current surges, improving protection margin for 3.3 V/5 V logic interfaces. |
| High-temperature operation (Tj max = 150 °C) | Supports placement near heat sources (e.g., MOSFETs, inductors) in compact power converters without derating. |
| IEC 61000-4-2 Level 4 compliance (±30 kV) | Meets stringent ESD immunity requirements for industrial HMI panels, USB-C ports, and Ethernet PHY interfaces. |
| Matte tin lead finish | Ensures solderability stability and whisker resistance per JESD201 Class 2, critical for long-life automotive and medical applications. |
Applications
| Industrial Power Supply Input Protection | Automotive Body Control Module (BCM) CAN Bus |
|---|---|
|
Use Scenario: 24 V DC input stage of DIN-rail mounted PLC power supply exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Primary surge clamp on main DC input rail, placed upstream of DC-DC converter and EMI filter. Use Value: Limits transient voltage to ≤25.2 V during 32.5 A surges, preventing overvoltage failure of upstream rectifier and downstream regulator ICs. |
Use Scenario: Bidirectional protection of CAN_H/CAN_L differential pair in vehicle door module subjected to ESD and battery transients. IC Role / Device Role / Timing Role: TVS pair (one per line) referenced to chassis ground, absorbing ±30 kV ESD and 4 kV EFT noise. Use Value: Maintains <100 pF junction capacitance at 0 V bias to preserve CAN signal integrity up to 1 Mbps without timing skew. |
| Telecom DSL Line Interface | Smart Meter AC Mains Surge Protection |
|
Use Scenario: Protection of ADSL/VDSL line driver/receiver circuitry connected to unshielded twisted-pair telephone lines. IC Role / Device Role / Timing Role: Secondary protection device after gas discharge tube (GDT), shunting induced lightning surges to ground. Use Value: Clamps 10/1000 µs surges to 25.2 V within nanoseconds, preventing latch-up in analog front-end op-amps and ADCs. |
Use Scenario: MOV-assisted primary surge protection stage in Class I smart meter, handling 6 kV/3 kA surges per IEC 61000-4-5. IC Role / Device Role / Timing Role: Fast-response secondary clamp across meter's isolated power supply input, limiting let-through voltage to MCU and RTC. Use Value: Delivers 1500 W peak power handling at 150 °C ambient, ensuring reliability in sealed, thermally constrained meter housings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18CA (Bourns) | Same 18 V VRM and bidirectional SMC package, but lower PPP = 600 W (10/1000 µs); VCL = 29.2 V at 1 A. | Limited to lower-energy surges; unsuitable for 1500 W IEC 61000-4-4 applications. | Select only when system-level surge testing confirms ≤600 W requirement and higher clamping voltage is acceptable. |
| P6SMB18CA (Littelfuse) | Identical VRM and SMC package, but IPP = 27.8 A (10/1000 µs); VCL = 27.7 V; RD = 0.052 Ω. | Higher clamping voltage reduces protection margin for 3.3 V/5 V systems; lower IPP limits surge endurance. | Prefer where cost sensitivity outweighs clamping performance, and thermal design accommodates higher VCL-induced power dissipation. |
Compared with SMBJ18CA and P6SMB18CA, SM15T18CA delivers superior surge robustness (1500 W vs. ≤600 W), tighter clamping (25.2 V vs. ≥27.7 V), and lower dynamic resistance - making it optimal for high-reliability industrial and automotive applications demanding full IEC 61000-4-4 compliance.
Availability
SM15T18CA is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, telecom line interfaces, and smart metering systems requiring stable component supply across extended product lifecycles.
Supply support for SM15T18CA 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 power management, analog, MEMS, and microcontroller technologies for industrial, automotive, and consumer markets.
SM15T18CA belongs to ST's SM15T series of high-power TVS diodes, engineered specifically for robust electrostatic and surge protection in harsh environments where reliability, temperature resilience, and low leakage are critical.
FAQ
What is the difference between SM15T18A and SM15T18CA?
SM15T18A is unidirectional (anode-to-cathode conduction only), intended for DC-biased lines like power rails. SM15T18CA is bidirectional, with symmetrical clamping in both polarities - required for AC-coupled signals, differential buses (e.g., RS-485, CAN), or floating references. Their VBR, VCL, and IPP values are identical, but CA devices lack polarity-dependent marking.
Can SM15T18CA be used in parallel for higher surge current handling?
No - paralleling TVS diodes without active current balancing causes uneven surge sharing due to VBR tolerances (±5 %). This risks thermal runaway in the lower-VBR unit. For >32.5 A needs, select a higher-rated part (e.g., SM20T18CA, 2000 W) or implement staged protection with GDT + TVS.
Does SM15T18CA meet UL 497B for telecom surge protection?
Yes - SM15T18CA carries UL 497B file number QVGQ2.E136224, certifying its suitability for primary and secondary telecom circuit protection per UL 497B Annex D. It satisfies insulation, flammability (UL94 V0), and surge withstand requirements for Type 1–3 protectors.
What is the recommended PCB footprint for SM15T18CA?
The official ST-recommended footprint is 8.19 mm × 5.11 mm (length × width), with 3.14 mm pad spacing and 1.54 mm pad width - matching IPC7531 and JEDEC MO-136AA standards. Adequate copper area (≥2 cm² per pad) is required to maintain thermal resistance ≤120 °C/W and sustain 1500 W pulse capability.
SM15T18CA 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:
- -
- Bidirectional Channels:
- 1
- 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
SM15T18CA FAQ
1.How can I place an order for SM15T18CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SM15T18CA 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 SM15T18CA reliable?
The price and inventory of SM15T18CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM15T18CA is usually 5 days.
3.What payment methods are accepted for SM15T18CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM15T18CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM15T18CA?
SM15T18CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM15T18CA 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 SM15T18CA?
For technical support, including SM15T18CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM15T18CA requirements.
6.How does Aetrix verify that SM15T18CA is sourced from the original manufacturer or authorized distributors?
All SM15T18CA 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 SM15T18CA meets industry standards.
7.What is the process for return or replacement of SM15T18CA?
All SM15T18CA units undergo pre-shipment inspection (PSI). If there is an issue with SM15T18CA, 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 SM15T18CA part is unused and in its original packaging.
Return procedure for SM15T18CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM15T18CA Tags
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