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STMicroelectronics SMAJ12CA-TR
- Part No.:
- SMAJ12CA-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ12CA-TR.pdf
- Description:
- TVS DIODE 12VWM 25.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:38,003
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Product details
Overview
SMAJ12CA-TR from STMicroelectronics is a bidirectional 400 W transient voltage suppression diode designed for ESD and surge protection in low-voltage DC interfaces. It features a 12 V standoff voltage (VRM), 19.9 V clamping voltage at 20.1 A (10/1000 µs), ≤1 µA leakage at 85 °C, and operates up to 150 °C junction temperature-used in USB ports, industrial I/O modules, and automotive body control units.
For engineers reviewing the SMAJ12CA-TR datasheet, SMAJ12CA-TR pinout, SMAJ12CA-TR application, or SMAJ12CA-TR equivalent, key selection criteria include bidirectional clamping behavior, low-leakage performance at elevated temperature, JEDEC DO-214AC (SMA) package compatibility, and IEC 61000-4-2/4-4 compliance for system-level ESD and EFT immunity design.
Technical Context
This TVS diode uses planar silicon junction technology to achieve stable breakdown characteristics and low dynamic resistance (0.259 Ω at 25 °C). Its bidirectional configuration enables symmetrical clamping for AC-coupled or floating signal lines without polarity constraints.
The device meets IEC 61000-4-2 level 4 (±30 kV contact/air discharge) and IEC 61000-4-4 level 4 (4 kV), with thermal design validated for FR4 PCBs using IPC-7531-compliant footprint and 70 µm copper thickness.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 12 V - Maximum continuous reverse working voltage before conduction begins |
| Clamping Voltage (VCL) | 19.9 V at 20.1 A (10/1000 µs) - Peak voltage seen by protected circuit during surge |
| Peak Pulse Power | 400 W (10/1000 µs) - Sustained surge energy handling capability per standard waveform |
| Leakage Current | ≤1 µA at 85 °C - Ensures minimal power loss and signal integrity in battery-powered systems |
| Junction Temp Range | –55 °C to +150 °C - Supports operation in under-hood automotive and industrial environments |
| Dynamic Resistance | 0.259 Ω at 25 °C - Low impedance limits voltage overshoot during fast transients |
Pinout & Package
Package: DO-214AC (SMA), JEDEC-registered surface-mount outline with 2.25–2.90 mm body width, 4.80–5.35 mm length, and 1.90–2.45 mm height. Compliant with IPC-7531 footprint and J-STD-020 MSL Level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Marked Band) | Reference terminal for bidirectional clamping | Identifies cathode end of die; both terminals behave identically in bidirectional mode |
| Anode | Reference terminal for bidirectional clamping | Electrically symmetric with cathode; no polarity dependency in CA variant |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables protection of AC-coupled or floating data lines (e.g., RS-485, CAN, audio) without external polarity management |
| Low leakage current | ≤1 µA at 85 °C ensures negligible standby current drain in always-on IoT sensors and battery-backed systems |
| High-temperature operation | Rated to +150 °C junction temperature supports placement near heat sources in motor drives and power supplies |
| IEC 61000-4-2/4-4 compliance | Validated to ±30 kV ESD (contact/air) and 4 kV EFT - reduces need for additional system-level filtering |
Applications
| USB 2.0 Port Protection | Industrial Digital I/O Module |
|---|---|
Use Scenario: Protecting USB D+/D− lines against ESD events during hot-plug insertion in embedded host controllers. IC Role / Device Role / Timing Role: Bidirectional TVS placed directly at connector to clamp transients before reaching PHY IC. Use Value: Prevents latch-up or damage to USB transceivers while maintaining <1 pF capacitance impact on signal integrity. | Use Scenario: Safeguarding 24 V digital input channels in PLC backplanes exposed to field wiring surges. IC Role / Device Role / Timing Role: Primary surge shunt across input terminals to divert 10/1000 µs transients induced by relay switching or lightning coupling. Use Value: Limits clamped voltage to 19.9 V, ensuring downstream optocoupler or MCU GPIO remains within safe operating range. |
| Automotive Body Control Unit | Smart Meter Communication Interface |
Use Scenario: Protecting LIN bus transceivers connected to door module actuators subject to load dump and ESD. IC Role / Device Role / Timing Role: Bidirectional TVS on LIN signal line to suppress coupled transients without disrupting DC bias. Use Value: Maintains signal fidelity during 12 V system operation while surviving repeated ±30 kV ESD strikes per IEC 61000-4-2. | Use Scenario: Shielding RS-485 transceivers in utility meters from surges on long-distance communication lines. IC Role / Device Role / Timing Role: Line-to-line and line-to-ground TVS pair protecting differential bus against 4 kV EFT per IEC 61000-4-4. Use Value: Clamps 20.1 A surge to 19.9 V, preventing transceiver latch-up and preserving data link reliability over 10+ year field life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ12CA-TR | 600 W peak pulse power (10/1000 µs), larger SMB package (DO-214AA) | Higher surge margin but requires more PCB area; less suitable for space-constrained USB ports | Select when system-level surge testing exceeds 400 W or board layout allows SMB footprint |
| SMCJ12CA-TR | 1500 W peak pulse power (10/1000 µs), SMC package (DO-214AB) | Designed for high-energy industrial mains-side protection; over-specified for signal-line use | Choose only if legacy designs mandate SMC footprint or require >1 kA surge current handling |
Compared with SMBJ12CA-TR and SMCJ12CA-TR, SMAJ12CA-TR offers optimal balance of surge robustness, compact size, and low leakage for signal-line protection-making it preferred for USB, RS-485, and automotive LIN where board space and thermal constraints are critical.
Availability
SMAJ12CA-TR is available at Aetrix Electronics and suitable for USB interface protection, industrial I/O modules, and automotive body control units requiring stable component supply and long-term obsolescence management.
Supply support for SMAJ12CA-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 intelligent power, sensing, and control solutions for automotive, industrial, and consumer markets.
SMAJxxCA belongs to ST's TVS Diode portfolio, engineered specifically for board-level ESD and surge immunity in space-constrained, high-reliability applications-emphasizing low leakage, high-temperature stability, and JEDEC-standard packaging.
FAQ
What is the difference between SMAJ12A-TR and SMAJ12CA-TR?
SMAJ12A-TR is unidirectional (anode-cathode asymmetry), intended for DC-biased lines like power rails; SMAJ12CA-TR is bidirectional, with identical clamping in both polarities, suited for AC-coupled or floating signals such as USB D+/D− or RS-485. Their marking codes differ (DUK vs. DBK), and CA devices show lower capacitance symmetry in high-frequency ESD events.
Does SMAJ12CA-TR meet automotive AEC-Q200 requirements?
No-SMAJ12CA-TR is not AEC-Q200 qualified. It is rated for industrial and commercial use with Tj max = 150 °C and MSL Level 1, but lacks the extended temperature cycling, vibration, and failure rate validation required for automotive qualification. For AEC-Q200-compliant alternatives, consider ST's Automotive-grade SMxJ series with explicit qualification documentation.
Can SMAJ12CA-TR be used for 24 V industrial power rail protection?
No-it is not recommended. With a 12 V standoff voltage, SMAJ12CA-TR will conduct continuously at 24 V, causing thermal runaway. For 24 V rail protection, select a TVS with VRM ≥ 28 V (e.g., SMAJ33CA-TR) to ensure safe steady-state operation while providing adequate clamping headroom above nominal voltage.
How does junction temperature affect clamping voltage in SMAJ12CA-TR?
Clamping voltage increases with junction temperature at a coefficient αT = 10⁻⁴ /°C. At 125 °C, VCL rises ~1% above its 25 °C value (19.9 V → ~20.1 V). This positive TC ensures predictable, non-catastrophic behavior under thermal stress-critical for sustained surge events in enclosed enclosures.
SMAJ12CA-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:
- -
- Bidirectional Channels:
- 1
- 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)
SMAJ12CA-TR FAQ
1.How can I place an order for SMAJ12CA-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ12CA-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 SMAJ12CA-TR reliable?
The price and inventory of SMAJ12CA-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ12CA-TR is usually 5 days.
3.What payment methods are accepted for SMAJ12CA-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ12CA-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ12CA-TR?
SMAJ12CA-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ12CA-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 SMAJ12CA-TR?
For technical support, including SMAJ12CA-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ12CA-TR requirements.
6.How does Aetrix verify that SMAJ12CA-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ12CA-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 SMAJ12CA-TR meets industry standards.
7.What is the process for return or replacement of SMAJ12CA-TR?
All SMAJ12CA-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ12CA-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 SMAJ12CA-TR part is unused and in its original packaging.
Return procedure for SMAJ12CA-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ12CA-TR Tags
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