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STMicroelectronics SMAJ70CA-TR
- Part No.:
- SMAJ70CA-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70CA-TR.pdf
- Description:
- TVS DIODE 70VWM 146VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:5,811
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Product details
Overview
SMAJ70CA-TR from STMicroelectronics is a bidirectional transient voltage suppression (TVS) diode designed for ESD and surge protection in DC power rails and signal lines. It features a 70 V standoff voltage (VRM), 113 V clamping voltage at 3.5 A (10/1000 µs), 400 W peak pulse power, and operates up to +150 °C junction temperature - deployed in industrial power supplies and automotive body control modules.
For engineers reviewing the SMAJ70CA-TR datasheet, SMAJ70CA-TR pinout, SMAJ70CA-TR application, or SMAJ70CA-TR equivalent, key selection criteria include bidirectional clamping behavior, low leakage (<0.2 µA @ 25 °C), JEDEC DO-214AC (SMA) package compatibility, and IEC 61000-4-2/4-4 level 4 compliance for robust system-level ESD immunity.
Technical Context
This TVS diode uses planar silicon junction technology to achieve stable breakdown characteristics and low dynamic resistance (3.75 Ω at 8/20 µs). Its bidirectional configuration enables symmetrical clamping on AC-coupled or floating signal paths without polarity constraints.
The device meets MIL-STD-883 method 3015 for ESD and IEC 61000-4-4 for fast transient bursts (4 kV), with thermal performance validated across -55 °C to +150 °C operating range and MSL Level 1 moisture sensitivity rating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 70 V - maximum continuous reverse working voltage before conduction begins |
| Breakdown Voltage (VBR) | 77.8–81.9 V @ 1 mA - precise avalanche onset threshold ensuring predictable turn-on |
| Clamping Voltage (VCL) | 113 V @ 3.5 A (10/1000 µs) - limits transient energy delivered to protected circuitry |
| Peak Pulse Power | 400 W (10/1000 µs) - sustains standard lightning-surge stress per IEC 61000-4-5 |
| Leakage Current | 0.2 µA @ 25 °C - minimizes standby power loss in battery-backed or high-impedance circuits |
| Junction Temperature | -55 to +150 °C - supports operation in under-hood automotive and industrial ambient environments |
| ESD Rating | ±30 kV contact/air discharge (IEC 61000-4-2 Level 4) - exceeds common system-level ESD immunity requirements |
Pinout & Package
Supplied in JEDEC DO-214AC (SMA) surface-mount package with two terminals: Cathode (K) and Anode (A). The bidirectional structure means both terminals function symmetrically as clamping nodes - no polarity marking required beyond standard SMA orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Transient current entry point (negative polarity event) | Conducts during negative transients; forms symmetrical clamping path with cathode |
| Cathode (K) | Transient current entry point (positive polarity event) | Conducts during positive transients; completes bidirectional clamping loop |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC signals or floating buses without external polarity management |
| Low dynamic resistance | 3.75 Ω at 8/20 µs - reduces clamping voltage overshoot during high-dI/dt surges |
| High-temperature reliability | Rated to +150 °C junction - maintains clamping stability in thermally constrained PCB layouts |
| JEDEC-compliant footprint | IPC-7531 SMA land pattern - ensures manufacturability and solder joint integrity in automated assembly |
| UL94 V0 flammability rating | Self-extinguishing epoxy molding compound - satisfies safety requirements for enclosed power systems |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module |
|---|---|
Use Scenario: Protecting 24 V DC input rails in programmable logic controllers against load dump and inductive switching spikes. IC Role / Device Role / Timing Role: Standoff-clamp TVS placed directly at connector entry point to shunt surge energy before reaching downstream regulators. Use Value: 113 V clamping ensures downstream 36 V-rated DC-DC converters remain within absolute maximum ratings during 400 W transients. | Use Scenario: Safeguarding LIN bus transceivers and microcontroller I/O pins from ESD events during vehicle assembly and service. IC Role / Device Role / Timing Role: Bidirectional TVS mounted at harness interface to clamp ±30 kV ESD pulses without polarity biasing. Use Value: Sub-µA leakage preserves sleep-mode current budget while maintaining full IEC 61000-4-2 Level 4 immunity. |
| Telecom Line Interface | Smart Meter Communication Port |
Use Scenario: Shielding RS-485 transceiver inputs in outdoor base station equipment exposed to induced lightning surges. IC Role / Device Role / Timing Role: Primary surge suppressor on differential pair, coordinated with secondary GDT or MOV for multi-stage protection. Use Value: 400 W (10/1000 µs) rating handles telecom-grade surge waveforms while 70 V VRM matches typical 48 V nominal line voltage. | Use Scenario: Securing PLC or RF module interfaces in utility smart meters subjected to field ESD and conducted noise. IC Role / Device Role / Timing Role: Final-stage TVS on communication port traces, placed immediately before connector to minimize inductance. Use Value: DO-214AC package allows compact placement near connectors; 150 °C rating accommodates sealed meter enclosures with elevated internal temperatures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ70CA-TR | Higher 600 W peak power (10/1000 µs); SMB package (DO-214AA) with larger pad area | Better suited for higher-energy surges where board space permits larger footprint | Select when surge threat exceeds 400 W but layout allows SMB size |
| SMCJ70CA-TR | 1500 W peak power (10/1000 µs); SMC package (DO-214AB) with enhanced thermal mass | Used in primary protection stages requiring higher energy absorption before secondary clamping | Choose for front-end protection where coordination with downstream TVS is required |
Compared with SMBJ70CA-TR and SMCJ70CA-TR, SMAJ70CA-TR offers optimal balance of compact DO-214AC footprint, 400 W capability, and low leakage - ideal for space-constrained secondary protection where moderate surge levels dominate.
Availability
SMAJ70CA-TR is available at Aetrix Electronics and suitable for industrial power supply protection, automotive body control modules, telecom line interface, and smart meter communication ports requiring stable component supply and long-term obsolescence management.
Supply support for SMAJ70CA-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, analog, MEMS, and microcontroller solutions across automotive, industrial, and consumer markets.
The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for high-reliability, low-leakage ESD and surge suppression in space- and thermally-constrained applications.
FAQ
What is the difference between SMAJ70CA-TR and SMAJ70A-TR?
SMAJ70CA-TR is bidirectional, providing symmetrical clamping for both positive and negative transients, while SMAJ70A-TR is unidirectional and requires correct polarity installation. The 'CA' suffix denotes bidirectional functionality, critical for AC-coupled or floating signal lines where polarity is undefined.
Can SMAJ70CA-TR be used in place of a unidirectional TVS in a DC rail?
Yes - SMAJ70CA-TR functions identically to a unidirectional device when installed across a DC rail, as its bidirectional structure clamps both overvoltage polarities. No circuit modification is needed, though it provides added margin against reverse-polarity faults or accidental miswiring.
What is the thermal resistance (Rth(j-a)) of SMAJ70CA-TR on a standard FR4 PCB?
On a standard FR4 board with 70 µm copper and recommended IPC-7531 footprint, Rth(j-a) is approximately 120 °C/W for short pulses. This value improves significantly with increased copper area - e.g., 2 cm² per pad reduces it to ~45 °C/W, enabling sustained surge handling at elevated ambient temperatures.
Does SMAJ70CA-TR meet automotive AEC-Q200 requirements?
No - SMAJ70CA-TR is not AEC-Q200 qualified. It is rated for industrial and commercial use with Tj up to +150 °C and meets IEC 61000-4-2/4-4, but lacks the extended temperature cycling, vibration, and lifetime testing required for automotive qualification. For AEC-Q200 applications, consider ST's Automotive-grade SMxJ series variants.
SMAJ70CA-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):
- 70V
- Voltage - Breakdown (Min):
- 77.8V
- Voltage - Clamping (Max) @ Ipp:
- 146V
- Current - Peak Pulse (10/1000µs):
- 16A (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)
SMAJ70CA-TR FAQ
1.How can I place an order for SMAJ70CA-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70CA-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 SMAJ70CA-TR reliable?
The price and inventory of SMAJ70CA-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70CA-TR is usually 5 days.
3.What payment methods are accepted for SMAJ70CA-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70CA-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70CA-TR?
SMAJ70CA-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70CA-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 SMAJ70CA-TR?
For technical support, including SMAJ70CA-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70CA-TR requirements.
6.How does Aetrix verify that SMAJ70CA-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ70CA-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 SMAJ70CA-TR meets industry standards.
7.What is the process for return or replacement of SMAJ70CA-TR?
All SMAJ70CA-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70CA-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 SMAJ70CA-TR part is unused and in its original packaging.
Return procedure for SMAJ70CA-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ70CA-TR Tags
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