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STMicroelectronics SM2T18A
- Part No.:
- SM2T18A
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-216AA
- Datasheet:
-
SM2T18A.pdf
- Description:
- TVS DIODE 16VWM 26VC DO216AA
- Quantity:
- Payment:
- Shipping:
Inventory:8,834
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Product details
Overview
SM2T18A from STMicroelectronics is a unidirectional Transil™ TVS diode designed for ESD and transient overvoltage protection in portable electronics. It features a 18 V standoff voltage (VRM), 17.1 V breakdown voltage (VBR), 26 V clamping voltage (VCL) at 7 A IPP, 500 pF junction capacitance, and 1.0 mm height in JEDEC DO-216AA (STmite) package - deployed in USB data lines and smartphone button interfaces.
For engineers reviewing the SM2T18A datasheet, SM2T18A pinout, SM2T18A application, or SM2T18A equivalent, key selection criteria include clamping performance under 8/20 µs surges, low-profile mounting compatibility with automated assembly, thermal resistance to PCB (Rth(j-a) = 250 °C/W), and leakage current ≤1 µA at 18 V.
Technical Context
The SM2T18A operates as a silicon avalanche diode with unidirectional polarity, triggered when reverse voltage exceeds its 17.1 V breakdown threshold. Its low clamping factor (VCL/VBR ≈ 1.52) ensures minimal voltage overshoot during transients up to 7 A peak pulse current (10/1000 µs).
Designed for surface-mount use on FR4 PCBs with recommended pad layout, it delivers 200 W peak pulse power (10/1000 µs) and 1000 W (8/20 µs), with junction-to-ambient thermal resistance of 250 °C/W and maximum junction temperature of 150 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - Maximum continuous reverse operating voltage before conduction begins |
| Breakdown Voltage (VBR) | 17.1 V @ 1 mA - Avalanche onset voltage defining turn-on threshold |
| Clamping Voltage (VCL) | 26 V @ 7 A - Peak voltage seen by protected circuit during 10/1000 µs surge |
| Junction Capacitance (Cj) | 500 pF @ 0 V - Signal integrity impact on high-speed lines like USB 2.0 |
| Leakage Current (IRM) | ≤1 µA @ 18 V - Minimal DC loading on battery-powered signal paths |
| Peak Pulse Power (PPP) | 200 W (10/1000 µs) - Sustained transient energy handling per IEC 61000-4-5 |
| Package Height | 1.0 mm - Enables ultra-thin device integration in smartphones and wearables |
Pinout & Package
SM2T18A uses the STmite package (JEDEC DO-216AA), a 2-terminal surface-mount case with cathode band marking. The device has no internal leads; both terminals are solderable metallized ends of the molded body.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Transient return path | Connected to ground or low-impedance return plane during clamping |
| Cathode | Protected line connection / Surge input | Connected to signal line (e.g., USB D+); marked with band |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile STmite package | 1.0 mm max height enables integration into space-constrained handheld PCBs |
| Fast response time | Sub-nanosecond turn-on ensures protection before IC damage occurs |
| Low clamping factor (VCL/VBR) | 1.52 ratio minimizes overvoltage stress on downstream 3.3 V or 5 V logic |
| ESD robustness | Rated for ±15 kV air discharge per IEC 61000-4-2 Level 4 |
| Pick-and-place compatible | DO-216AA geometry supports automated SMT placement and AOI inspection |
Applications
| USB 2.0 Data Lines | Smartphone Side Buttons |
|---|---|
Use Scenario: Protecting D+ and D− lines against ESD events during cable insertion and handling. IC Role / Device Role: Unidirectional TVS clamp placed between connector and USB transceiver IC. Use Value: 500 pF capacitance avoids signal integrity degradation while clamping to 26 V at 7 A. | Use Scenario: Shielding mechanical button traces from user-induced ESD in compact front bezel layouts. IC Role / Device Role: Standoff-rated (18 V) transient suppressor tied between button trace and system ground. Use Value: 1.0 mm height fits beneath thin metal domes; ≤1 µA leakage preserves battery life. |
| Bluetooth Audio Module Antenna Feed | Wearable Heart Rate Sensor Interface |
Use Scenario: Suppressing RF-coupled transients on 2.4 GHz antenna feed lines near battery charging circuits. IC Role / Device Role: Low-capacitance TVS placed in series with matching network to limit voltage excursion. Use Value: 500 pF allows minimal detuning of 50 Ω impedance; 26 V clamping protects LNA input stage. | Use Scenario: Guarding analog photodiode signal paths from ESD during wristband contact and flex cycling. IC Role / Device Role: Bidirectionally referenced (via unidirectional configuration with local ground) transient shunt. Use Value: 17.1 V VBR aligns with 3.3 V rail margin; 250 °C/W Rth(j-a) supports thermal stability on small flex PCBs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | DO-214AC package (2.79 mm height); 24.4 V VCL @ 7.5 A; 600 pF Cj | Higher profile limits use in <1.2 mm Z-height designs; higher capacitance affects >480 Mbps signals | Select when board clearance >2.5 mm and USB 1.1 speed suffices |
| 1.5SMC18A | DO-214AB package (2.4 mm height); 29.2 V VCL @ 5.1 A; 350 pF Cj | Lower capacitance benefits RF/analog paths but higher clamping risks 3.3 V IO tolerance | Prefer for RF front-end protection where clamping margin >3 V is acceptable |
Compared with SMAJ18A and 1.5SMC18A, SM2T18A offers the lowest profile (1.0 mm) and best clamping ratio (1.52), making it optimal for modern ultra-thin portable devices requiring tight voltage margins and strict mechanical constraints.
Availability
SM2T18A is available at Aetrix Electronics and suitable for USB interface protection, smartphone button ESD hardening, and wearable sensor signal line safeguarding requiring stable component supply across high-mix consumer electronics production.
Supply support for SM2T18A 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, specializing in power management, analog, MEMS, and automotive ICs with broad industrial and consumer reach.
The SM2T series belongs to ST's Transil™ TVS portfolio, engineered specifically for miniaturized portable electronics needing low-height, high-reliability ESD protection without compromising signal fidelity.
FAQ
What is the maximum peak pulse current the SM2T18A can handle?
The SM2T18A is rated for 7 A peak pulse current (IPP) under 10/1000 µs waveform conditions, delivering 200 W peak pulse power. At the shorter 8/20 µs surge (IEC 61000-4-5), it supports up to 1000 W, corresponding to ~38.5 A based on VCL = 26 V and standard derating curves in the datasheet.
Is the SM2T18A bidirectional or unidirectional?
SM2T18A is a unidirectional TVS diode, indicated by its single cathode band marking and electrical specification table listing only reverse characteristics (VRM, VBR, VCL). It conducts only during negative transients on the cathode side and must be oriented with cathode toward the protected line.
How does the SM2T18A's 1.0 mm height affect PCB layout?
The 1.0 mm maximum height enables placement under mechanical components such as metal domes or display bezels and reduces board-level warpage risk during reflow. Its DO-216AA footprint requires 1.75 × 1.75 mm pad area per terminal, with 2.67 mm overall length - critical for routing density in compact mobile PCBs.
Can SM2T18A replace SM2T14A in a design?
No - SM2T18A has higher standoff (18 V vs. 14 V) and breakdown (17.1 V vs. 13.3 V), resulting in delayed turn-on and higher clamping (26 V vs. 19.9 V). Substituting it risks insufficient protection for 12 V nominal systems. Verify VBR alignment with protected IC's absolute maximum ratings before interchange.
SM2T18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-216AA
- Series:
- SM2T, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 16V
- Voltage - Breakdown (Min):
- 17.1V
- Voltage - Clamping (Max) @ Ipp:
- 26V
- Current - Peak Pulse (10/1000µs):
- 7A
- Power - Peak Pulse:
- 200W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-216AA
SM2T18A FAQ
1.How can I place an order for SM2T18A through Aetrix?
Please submit a Request for Quotation (RFQ) for SM2T18A 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 SM2T18A reliable?
The price and inventory of SM2T18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM2T18A is usually 5 days.
3.What payment methods are accepted for SM2T18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM2T18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM2T18A?
SM2T18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM2T18A 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 SM2T18A?
For technical support, including SM2T18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM2T18A requirements.
6.How does Aetrix verify that SM2T18A is sourced from the original manufacturer or authorized distributors?
All SM2T18A 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 SM2T18A meets industry standards.
7.What is the process for return or replacement of SM2T18A?
All SM2T18A units undergo pre-shipment inspection (PSI). If there is an issue with SM2T18A, 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 SM2T18A part is unused and in its original packaging.
Return procedure for SM2T18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM2T18A Tags
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