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STMicroelectronics SMA6J18A-TR
- Part No.:
- SMA6J18A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMA6J18A-TR.pdf
- Description:
- TVS DIODE 18VWM 33.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:8,707
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Product details
Overview
SMA6J18A-TR from STMicroelectronics is a unidirectional 600 W transient voltage suppression (TVS) diode designed for primary-level ESD and surge protection in DC power rails and signal lines. It features a standoff voltage (VRM) of 18 V, clamping voltage (VCL) of 28.3 V at 21.5 A (10/1000 µs), and operates up to 175 °C junction temperature - enabling robust protection in automotive body control modules, industrial PLC I/O ports, and telecom power supplies.
For engineers reviewing the SMA6J18A-TR datasheet, SMA6J18A-TR pinout, SMA6J18A-TR application, or SMA6J18A-TR equivalent, key selection criteria include its 28.3 V clamping performance at 21.5 A surge current, low leakage (<0.2 µA @ 25 °C), JEDEC DO-214AC (SMA) package compatibility, and IEC 61000-4-2 Level 4 (±30 kV contact/air) compliance.
Technical Context
This TVS diode uses planar silicon technology to achieve stable breakdown characteristics and low dynamic resistance (RD = 0.288 Ω) under 10/1000 µs surges. Its unidirectional configuration provides asymmetric clamping - forward conduction during overvoltage events on positive-polarity rails while blocking reverse leakage below 18 V.
The device meets MIL-STD-883 Method 3015 for ESD immunity and IEC 61000-4-4 Level 4 (4 kV) for electrical fast transients. Thermal design is supported by validated junction-to-ambient thermal resistance curves referenced to IPC-7531-compliant copper footprints.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - maximum continuous reverse operating voltage before clamping begins |
| Breakdown Voltage (VBR) | 20.0–22.1 V @ 1 mA - precise avalanche initiation threshold ensuring predictable turn-on |
| Clamping Voltage (VCL) | 28.3 V @ 21.5 A (10/1000 µs) - limits downstream voltage stress during surge events |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - sustains high-energy transients without failure in standard PCB layouts |
| Leakage Current (IRM) | ≤0.2 µA @ 25 °C - minimizes standby power loss in battery-backed or low-power systems |
| Junction Temperature Range | −55 to +175 °C - supports operation in under-hood automotive and industrial environments |
| ESD Rating | ±30 kV contact & air discharge (IEC 61000-4-2 Level 4) - exceeds common system-level ESD requirements |
Pinout & Package
Package: DO-214AC (SMA), JEDEC-registered outline with matte tin-plated leads, UL94 V0 resin, and IPC-7531-compliant footprint (5.43 mm × 2.63 mm pad pitch).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked band) | Surge current sink node | Connected to protected line; conducts avalanche current to ground during overvoltage |
| Anode | Reference/return path | Typically tied to system ground or low-impedance return plane for effective clamping |
Key Features
| Feature | Design Value |
|---|---|
| Low dynamic resistance | 0.288 Ω - reduces clamping voltage rise under high-current surges, improving protection margin |
| High-temperature reliability | 175 °C max Tj - enables placement near heat sources (e.g., power converters) without derating |
| UL94 V0 flammability rating | Self-extinguishing epoxy housing - satisfies safety requirements for enclosed industrial equipment |
| MSL Level 1 moisture sensitivity | No dry-pack or bake required before reflow - simplifies SMT assembly and reduces handling cost |
Applications
| Automotive Body Control Module | Industrial PLC Digital Input |
|---|---|
|
Use Scenario: Protecting 12 V supply rail and LIN bus lines against load dump and ESD in door module ECUs. IC Role / Device Role / Timing Role: Primary overvoltage clamp on power input and communication lines, responding within nanoseconds to transients. Use Value: Prevents latch-up or damage to MCU I/O and transceivers by limiting voltage to ≤28.3 V during 21.5 A surges. |
Use Scenario: Safeguarding 24 V digital input channels from field-wiring induced surges and operator ESD. IC Role / Device Role / Timing Role: Front-end transient suppressor placed before optocoupler or Schmitt trigger input stage. Use Value: Maintains signal integrity by clamping transients before they propagate into isolation barriers or logic circuitry. |
| Telecom Power Supply Input | Smart Meter Battery Backup Circuit |
|
Use Scenario: Guarding AC/DC adapter output against lightning-induced surges on 24–48 V distribution lines. IC Role / Device Role / Timing Role: Secondary-side TVS on regulated DC bus, coordinated with upstream MOVs and fuses. Use Value: Delivers 600 W peak pulse handling without degradation, supporting long-term field reliability per IEC 61000-4-4. |
Use Scenario: Shielding lithium coin-cell backup path from ESD during battery replacement or terminal contact. IC Role / Device Role / Timing Role: Low-leakage (0.2 µA) protector on VBAT rail to avoid accelerating battery self-discharge. Use Value: Ensures >10-year shelf life in metering applications by minimizing parasitic current drain under normal bias. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMA6J18CA-TR | Bidirectional version; symmetric clamping (±28.3 V); same VRM, VBR, and PPP ratings | Required for AC-coupled or dual-polarity signal lines (e.g., RS-485, CAN bus) | Select when protecting bidirectional interfaces where reverse polarity transients must also be suppressed |
| SMBJ18A | Same electrical specs but in larger SMB (DO-214AA) package; 600 W rating, 28.3 V VCL, 0.2 µA IRM | Higher thermal mass allows slightly better sustained surge handling; occupies more PCB area | Choose when board layout permits larger footprint and enhanced thermal margin is prioritized over space efficiency |
Compared with SMA6J18CA-TR, the unidirectional SMA6J18A-TR offers lower capacitance and tighter clamping on positive transients; versus SMBJ18A, it delivers identical protection in a 30% smaller footprint - critical for dense automotive and IoT PCBs.
Availability
SMA6J18A-TR is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O protection, and telecom power supply designs requiring stable component supply across multi-year production cycles.
Supply support for SMA6J18A-TR 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.
SMA6JxxA belongs to ST's high-reliability TVS diode product line, engineered specifically for robust front-end surge and ESD protection in harsh-environment applications demanding extended temperature range and long-term stability.
FAQ
What is the maximum clamping voltage of SMA6J18A-TR under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 28.3 V at 21.5 A for a 10/1000 µs waveform, measured at 25 °C ambient. This value increases with junction temperature due to the positive temperature coefficient (αT = 10⁻⁴/°C), reaching ~30.1 V at 125 °C junction temperature.
Can SMA6J18A-TR be used in bidirectional signal lines like RS-485?
No - SMA6J18A-TR is unidirectional and only clamps positive overvoltages relative to ground. For RS-485 or other AC-coupled or differential interfaces, the bidirectional SMA6J18CA-TR must be used to suppress transients on both polarities.
Does this TVS diode require special PCB layout considerations?
Yes - ST recommends using the IPC-7531-compliant SMA footprint (5.43 mm × 2.63 mm pad pitch) with ≥1 cm² of 70 µm copper per lead to maintain thermal resistance below 100 °C/W. Minimizing trace inductance between cathode and ground plane is critical for optimal clamping response.
How does SMA6J18A-TR compare to older SMAJ18A in terms of surge capability?
SMA6J18A-TR offers identical 600 W (10/1000 µs) rating but improves upon SMAJ18A with lower dynamic resistance (0.288 Ω vs. ~0.35 Ω), higher temperature rating (175 °C vs. 150 °C), and updated JEDEC DO-214AC package alignment - enhancing long-term reliability in modern automotive and industrial deployments.
SMA6J18A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SMA6J, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 33.2V
- Current - Peak Pulse (10/1000µs):
- 102A (8/20µs)
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMA6J18A-TR FAQ
1.How can I place an order for SMA6J18A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA6J18A-TR 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 SMA6J18A-TR reliable?
The price and inventory of SMA6J18A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA6J18A-TR is usually 5 days.
3.What payment methods are accepted for SMA6J18A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA6J18A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA6J18A-TR?
SMA6J18A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA6J18A-TR 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 SMA6J18A-TR?
For technical support, including SMA6J18A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA6J18A-TR requirements.
6.How does Aetrix verify that SMA6J18A-TR is sourced from the original manufacturer or authorized distributors?
All SMA6J18A-TR 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 SMA6J18A-TR meets industry standards.
7.What is the process for return or replacement of SMA6J18A-TR?
All SMA6J18A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMA6J18A-TR, 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 SMA6J18A-TR part is unused and in its original packaging.
Return procedure for SMA6J18A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMA6J18A-TR Tags
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