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STMicroelectronics SMAJ12A-TR
- Part No.:
- SMAJ12A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ12A-TR.pdf
- Description:
- TVS DIODE 12VWM 25.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:24,384
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Product details
Overview
SMAJ12A-TR from STMicroelectronics is a unidirectional 400 W transient voltage suppression (TVS) diode designed for primary-level ESD and surge protection in DC power rails and signal lines. It features a 12 V standoff voltage (VRM), 19.9 V clamping voltage at 20.1 A (10/1000 µs), 0.2 µA leakage at 25 °C, and operates up to 150 °C junction temperature - deployed in industrial power supplies and automotive body control modules.
For engineers reviewing the SMAJ12A-TR datasheet, SMAJ12A-TR pinout, SMAJ12A-TR application, or SMAJ12A-TR equivalent, key selection criteria include clamping performance under IEC 61000-4-2 (30 kV contact/air), low-leakage operation at elevated temperature, JEDEC DO-214AC (SMA) package compatibility, and 400 W peak pulse power rating at Tj = 25 °C.
Technical Context
This TVS diode uses planar silicon junction technology to achieve stable breakdown behavior and low dynamic resistance (0.259 Ω at 25 °C). Its unidirectional configuration enables asymmetric clamping on positive-going transients while blocking reverse current below VRM = 12 V.
The device meets IEC 61000-4-4 Level 4 (4 kV) and exceeds IEC 61000-4-2 Level 4 (30 kV air/contact discharge), with thermal design validated per JESD22-B102 E3 and MIL-STD-750 Method 2026 solderability standards. Junction-to-ambient thermal resistance is optimized for FR4 PCBs with recommended 1.4 × 5.4 mm footprint.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 12 V - maximum continuous reverse operating voltage before conduction begins |
| Clamping Voltage (VCL) | 19.9 V at 20.1 A (10/1000 µs) - limits surge-induced voltage across protected circuitry |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs) - defines maximum transient energy absorption capability at 25 °C |
| Leakage Current (IRM) | 0.2 µA at 25 °C - ensures minimal standby power loss in high-impedance sensing or battery-backed circuits |
| Junction Temperature Range | –55 °C to +150 °C - supports operation in under-hood automotive and industrial environments |
| Dynamic Resistance (RD) | 0.259 Ω - determines voltage rise per ampere of surge current beyond clamping threshold |
| ESD Rating | 30 kV contact & air discharge (IEC 61000-4-2) - qualifies for direct human-body model interface protection |
Pinout & Package
Package: JEDEC DO-214AC (SMA), surface-mount, single-diode configuration with cathode band marking. Dimensions: 4.80–5.35 mm length (E), 2.25–2.90 mm width (D), 1.90–2.45 mm height (A1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry during forward surge | Connected to protected line; conducts only during positive overvoltage events |
| Cathode | Current exit / reference node | Typically tied to ground or lower-potential rail; carries full surge current to sink |
Key Features
| Feature | Design Value |
|---|---|
| Low leakage at high temperature | 1 µA max at 85 °C - maintains signal integrity in thermally stressed sensor interfaces |
| High surge robustness | 2.3 kW peak power (8/20 µs) - withstands lightning-induced surges in telecom and PoE applications |
| JEDEC-compliant footprint | IPC-7531 standard SMA pad layout - ensures manufacturability and thermal reliability on FR4 |
| RoHS-compliant plating | Matt tin-plated leads per J-STD-002 - eliminates whisker risk and supports lead-free reflow |
| Stable clamping over temperature | αT = 8.3 × 10⁻⁴ /°C - predictable VCL drift enables accurate system-level overvoltage margining |
Applications
| Industrial Power Supply Input Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: 12 V DC input rail exposed to load-dump and jump-start transients in factory automation controllers. IC Role / Device Role / Timing Role: Primary clamping element placed upstream of DC-DC converter input to limit voltage excursion to ≤20 V. Use Value: Prevents damage to downstream regulators by absorbing 400 W surges without degradation over >10⁵ events. |
Use Scenario: LIN bus transceiver power supply line subject to ISO 7637-2 Pulse 1/2a/5a in vehicle door modules. IC Role / Device Role / Timing Role: Unidirectional TVS shunting negative transients and clamping positive spikes above 12 V. Use Value: Meets OEM requirements for 150 °C ambient operation and 30 kV ESD immunity per IEC 61000-4-2. |
| Telecom Equipment DC Feeds | Smart Meter Power Input Stage |
Use Scenario: –48 V DC power feed in remote radio units experiencing induced surges from nearby lightning strikes. IC Role / Device Role / Timing Role: Reverse-biased protection on negative rail, conducting only during overvoltage events exceeding |12 V|. Use Value: Clamps 8/20 µs surges to ≤25.3 V at 91 A, preserving isolation barrier integrity in PoE-powered systems. |
Use Scenario: Mains-derived 12 V auxiliary supply in utility meters subjected to conducted surges per IEC 61000-4-4 Level 4. IC Role / Device Role / Timing Role: First-line defense on AC/DC converter output, limiting transient propagation to microcontroller power domain. Use Value: Enables 10-year field reliability with <0.2 µA leakage ensuring battery backup runtime remains unaffected. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ12AHE3_A/H (Vishay) | Same VRM (12 V), slightly higher VCL (20.1 V @ 20.1 A), identical DO-214AC package | Approved for automotive AEC-Q101; tighter VBR tolerance (±5% vs ±10%) | Select when AEC-Q101 qualification and tighter parametric consistency are required |
| P6SMB12A (ON Semiconductor) | Same VRM and package; lower PPP (600 W), higher IRM (1 µA @ 25 °C) | Higher clamping voltage (21.2 V @ 23.3 A); suited for less sensitive loads | Choose where cost sensitivity outweighs clamping precision and leakage constraints |
Compared with SMAJ12A-TR, SMAJ12AHE3_A/H offers enhanced automotive qualification and tighter VBR control but no improvement in leakage or thermal derating; P6SMB12A trades clamping performance and leakage for broader availability and lower unit cost in non-critical applications.
Availability
SMAJ12A-TR is available at Aetrix Electronics and suitable for industrial power supply input protection, automotive body control modules, telecom equipment DC feeds, and smart meter power input stages requiring stable component supply and long-term lifecycle support.
Supply support for SMAJ12A-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, delivering innovative solutions across automotive, industrial, power, and IoT markets with strong manufacturing and R&D infrastructure.
The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for high-reliability ESD and surge suppression in harsh-environment applications where low leakage, thermal stability, and standardized packaging are critical.
FAQ
What is the maximum clamping voltage of SMAJ12A-TR under a 10/1000 µs surge?
The maximum clamping voltage is 19.9 V at 20.1 A for a 10/1000 µs waveform, measured at Tj = 25 °C. This value increases with junction temperature at a coefficient of 8.3 × 10⁻⁴ /°C, reaching approximately 21.2 V at 125 °C under the same current.
Can SMAJ12A-TR be used in bidirectional signal line protection?
No - SMAJ12A-TR is unidirectional and only protects against positive transients relative to its cathode. For bidirectional signal lines such as USB or RS-485, the SMAJ12CA variant must be used, which provides symmetrical clamping for both polarities.
Is SMAJ12A-TR compatible with lead-free reflow processes?
Yes - it complies with J-STD-020 MSL Level 1 and supports peak reflow temperatures up to 245 °C for ≤30 seconds, matching standard lead-free profiles. Its matte tin-plated leads meet JESD-201 Class 2 whisker resistance requirements.
How does the 0.2 µA leakage current impact low-power sensor designs?
At 0.2 µA (25 °C), leakage introduces negligible error in high-impedance sensor bias networks (<0.1 mV drop across 100 kΩ), preserving ADC accuracy and enabling multi-year battery life in always-on environmental monitors without compromising protection integrity.
SMAJ12A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ, 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:
- 25.3V
- Current - Peak Pulse (10/1000µs):
- 91A (8/20µs)
- Power - Peak Pulse:
- 400W
- 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:
- DO-214AC (SMA)
SMAJ12A-TR FAQ
1.How can I place an order for SMAJ12A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ12A-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 SMAJ12A-TR reliable?
The price and inventory of SMAJ12A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ12A-TR is usually 5 days.
3.What payment methods are accepted for SMAJ12A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ12A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ12A-TR?
SMAJ12A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ12A-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 SMAJ12A-TR?
For technical support, including SMAJ12A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ12A-TR requirements.
6.How does Aetrix verify that SMAJ12A-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ12A-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 SMAJ12A-TR meets industry standards.
7.What is the process for return or replacement of SMAJ12A-TR?
All SMAJ12A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ12A-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 SMAJ12A-TR part is unused and in its original packaging.
Return procedure for SMAJ12A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ12A-TR Tags
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