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STMicroelectronics SMBJ12A-TR
- Part No.:
- SMBJ12A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ12A-TR.pdf
- Description:
- TVS DIODE 12VWM 19.9VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:23,915
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Product details
Overview
SMBJ12A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for primary-level surge protection on DC power rails and signal lines. It features a 12 V stand-off voltage (VRM), 13.3 V minimum breakdown voltage (VBR), 19.9 V clamping voltage (VCL) at 31 A peak pulse current (IPP), and 600 W peak pulse power rating (10/1000 µs) - enabling robust ESD and lightning-induced transient suppression in industrial power supplies and automotive body electronics.
For engineers reviewing the SMBJ12A-TR datasheet, SMBJ12A-TR pinout, SMBJ12A-TR application, or SMBJ12A-TR equivalent, key selection criteria include clamping voltage margin vs. protected IC's absolute maximum rating, leakage current at elevated temperature (≤1 µA @ 85 °C), junction temperature capability (up to +150 °C), and UL497B recognition for isolated loop circuit protection.
Technical Context
This TVS diode operates as a voltage-clamped shunt protector: under normal bias (VRM = 12 V), it exhibits ultra-low reverse leakage (0.2 µA @ 25 °C); during transients exceeding VBR (13.3–14.0 V), it avalanches rapidly (<1 ns response) to clamp voltage at ≤19.9 V (10/1000 µs) or ≤25.3 V (8/20 µs), diverting up to 31 A or 157 A respectively.
Its planar silicon junction delivers stable dynamic resistance (RD = 0.168 Ω @ 10/1000 µs), low thermal impedance (Zth(j-a) < 100 °C/W on standard FR4), and high reliability under repeated surges - validated per IEC 61000-4-2 (±30 kV contact/air), IEC 61000-4-4 (4 kV level 4), and UL497B (file E136224) for isolated loop applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 12 V - Maximum continuous reverse operating voltage before significant leakage begins. |
| Breakdown Voltage (VBR) | 13.3–14.0 V @ 1 mA - Confirmed avalanche onset range ensuring reliable triggering above system nominal voltage. |
| Clamping Voltage (VCL) | 19.9 V @ 31 A (10/1000 µs) - Limits transient voltage seen by downstream ICs to safe levels. |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - Sustains high-energy surges typical of inductive switching and EFT events. |
| Leakage Current (IRM) | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Ensures minimal power loss and signal integrity in always-on circuits. |
| Junction Temperature (Tj) | -55 to +150 °C - Supports operation in under-hood automotive and industrial ambient environments. |
| UL Recognition | UL497B (E136224) - Certified for use as an isolated loop circuit protector in telecom and industrial interfaces. |
Pinout & Package
Package: SMB (DO-214AA), surface-mount, 2-terminal device with matte tin-plated leads compliant with J-STD-020 MSL Level 1 and IPC7531 footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked band) | Surge return path | Connected to ground or low-impedance reference; conducts avalanche current during overvoltage events. |
| Anode | Protected line input | Connected to the line being protected (e.g., 12 V rail or CAN-H); reverse-biased during normal operation. |
Key Features
| Feature | Design Value |
|---|---|
| Low clamping ratio (VCL/VBR ≈ 1.5) | Ensures tight voltage margin between breakdown and clamping, minimizing stress on protected devices. |
| High surge robustness (4 kW @ 8/20 µs) | Withstands severe lightning-induced surges common in outdoor and industrial installations. |
| Stable leakage across temperature | 0.2 µA @ 25 °C → 1 µA @ 85 °C enables reliable long-term operation in thermally demanding enclosures. |
| UL497B certified isolation rating | Validates suitability for protecting secondary-side circuits in isolated power and communication interfaces. |
| Planar junction construction | Delivers consistent parametric performance and improved reliability vs. older diffused-junction TVS diodes. |
Applications
| Industrial PLC I/O Modules | Automotive Body Control Units |
|---|---|
Use Scenario: 24 V DC input channels exposed to load dump and relay coil flyback in factory automation cabinets. IC Role / Device Role / Timing Role: Primary shunt protector placed upstream of input conditioning circuitry and microcontroller GPIOs. Use Value: Clamps transients to ≤19.9 V, preventing damage to 3.3 V/5 V logic interfaces while maintaining <1 µA leakage at 85 °C ambient. | Use Scenario: LIN bus or switched 12 V supply lines in door modules subject to ESD and battery reversal transients. IC Role / Device Role / Timing Role: Unidirectional TVS on power rail and data line, referenced to chassis ground. Use Value: UL497B certification ensures compliance with automotive isolated-loop safety requirements; 150 °C Tj rating supports under-dash mounting. |
| Telecom Power Feeds | Smart Meter DC Power Inputs |
Use Scenario: -48 V DC power interface in remote radio units exposed to induced surges from nearby lightning strikes. IC Role / Device Role / Timing Role: First-stage surge suppressor on primary side of isolated DC/DC converter. Use Value: 600 W (10/1000 µs) rating handles sustained energy from coupled surges; low RD (0.168 Ω) minimizes clamping overshoot. | Use Scenario: 12 V auxiliary power input in utility meters installed in outdoor meter boxes. IC Role / Device Role / Timing Role: Standoff-rated TVS on main DC input, coordinated with secondary MOV or GDT stages. Use Value: 12 V VRM matches nominal supply; 19.9 V VCL ensures compatibility with 24 V-rated input capacitors and regulators. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ12CA-TR | Bidirectional version; symmetric clamping (±19.9 V) with same VRM and VBR. | Required for AC-coupled or differential signal lines (e.g., RS-485, CAN) where polarity reversal occurs. | Select when protecting bidirectional signals or floating references; not interchangeable with SMBJ12A-TR in unidirectional DC rails. |
| SMAJ12A-TR | Lower PPP rating (400 W vs. 600 W); identical VRM/VBR but higher VCL (23.2 V @ 17.3 A). | Suitable for lower-energy transients; insufficient for IEC 61000-4-4 level 4 (4 kV) in high-impedance source scenarios. | Use only where space constraints force SMA package; verify clamping margin against protected IC's max rating due to higher VCL. |
Compared with SMBJ12CA-TR and SMAJ12A-TR, SMBJ12A-TR uniquely balances 600 W surge capacity, low 19.9 V clamping, and UL497B certification - making it optimal for unidirectional 12 V DC power rail protection where reliability under repeated high-energy transients is critical.
Availability
SMBJ12A-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and smart meter DC power inputs requiring stable component supply, long-lifecycle support, and traceable sourcing.
Supply support for SMBJ12A-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 analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.
The SMBJ series belongs to ST's high-reliability TVS portfolio, engineered specifically for robust transient suppression in harsh environments - emphasizing low leakage, high Tj operation, and international safety certifications like UL497B and IEC 61000-4-x.
FAQ
What is the maximum clamping voltage of SMBJ12A-TR under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 19.9 V at 31 A peak pulse current for a 10/1000 µs waveform, measured at 25 °C. This value increases linearly with junction temperature per αT = 8.3 × 10⁻⁴/°C, reaching ~21.2 V at 125 °C junction temperature.
Is SMBJ12A-TR suitable for protecting a 12 V automotive power rail?
Yes - its 12 V stand-off voltage (VRM) aligns with nominal 12 V systems, and its 19.9 V clamping voltage stays below the 24 V absolute maximum rating of most automotive-grade regulators and microcontrollers. UL497B certification further validates its use in isolated-loop automotive subsystems.
How does SMBJ12A-TR differ from SMBJ12CA-TR in circuit implementation?
SMBJ12A-TR is unidirectional and must be oriented with cathode toward ground; SMBJ12CA-TR is bidirectional and symmetrical, allowing placement on AC or differential lines without polarity concern. They share identical VRM, VBR, and VCL magnitudes but differ in conduction directionality and marking (BUE vs. BBE).
Does SMBJ12A-TR require derating at elevated ambient temperatures?
Yes - its peak pulse power rating decreases with rising junction temperature: from 600 W at 25 °C to ~350 W at 150 °C (per Figure 3). Designers must calculate thermal resistance (Rth(j-a)) based on PCB copper area and ensure Tj remains ≤150 °C under worst-case surge repetition and ambient conditions.
SMBJ12A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJ, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 12V
- Voltage - Breakdown (Min):
- 13.3V
- Voltage - Clamping (Max) @ Ipp:
- 19.9V
- Current - Peak Pulse (10/1000µs):
- 31A
- Power - Peak Pulse:
- 600W
- 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:
- SMB
SMBJ12A-TR FAQ
1.How can I place an order for SMBJ12A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ12A-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 SMBJ12A-TR reliable?
The price and inventory of SMBJ12A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ12A-TR is usually 5 days.
3.What payment methods are accepted for SMBJ12A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ12A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ12A-TR?
SMBJ12A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ12A-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 SMBJ12A-TR?
For technical support, including SMBJ12A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ12A-TR requirements.
6.How does Aetrix verify that SMBJ12A-TR is sourced from the original manufacturer or authorized distributors?
All SMBJ12A-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 SMBJ12A-TR meets industry standards.
7.What is the process for return or replacement of SMBJ12A-TR?
All SMBJ12A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ12A-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 SMBJ12A-TR part is unused and in its original packaging.
Return procedure for SMBJ12A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ12A-TR Tags
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