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STMicroelectronics SMAJ70A-TR
- Part No.:
- SMAJ70A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70A-TR.pdf
- Description:
- TVS DIODE 70VWM 146VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:18,510
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Product details
Overview
SMAJ70A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for robust 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 rating, and low leakage current of 0.2 µA at 25 °C - deployed in industrial power supplies and automotive body control modules.
For engineers reviewing the SMAJ70A-TR datasheet, SMAJ70A-TR pinout, SMAJ70A-TR application, or SMAJ70A-TR equivalent, key selection criteria include clamping voltage margin vs. protected IC VDD, junction temperature derating above 85 °C, IEC 61000-4-2/4-4 compliance level, and SMA footprint compatibility with IPC 7531 layout standards.
Technical Context
This TVS diode operates as a voltage-clamped shunt protector: under normal bias it presents <0.2 µA reverse leakage up to 70 V; during transients exceeding VBR (min. 77.8 V), it avalanches to clamp voltage ≤113 V at 3.5 A (10/1000 µs). Its planar junction enables stable performance across –55 °C to +150 °C operating junction range.
The device complies with IEC 61000-4-2 (30 kV air/contact discharge) and IEC 61000-4-4 Level 4 (4 kV), with dynamic resistance of 3.75 Ω at 8/20 µs surge - critical for limiting let-through energy to downstream MOSFETs or microcontrollers in 24 V industrial I/O circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 70 V - maximum continuous reverse working voltage before leakage exceeds 0.2 µA; sets upper limit for protected rail voltage. |
| Breakdown Voltage (VBR min) | 77.8 V at 1 mA - guaranteed avalanche initiation threshold; ensures reliable triggering before system overvoltage damage. |
| Clamping Voltage (VCL) | 113 V at 3.5 A (10/1000 µs) - peak voltage seen by protected circuit during standardized surge; defines safe margin vs. IC absolute max ratings. |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs) - maximum transient energy dissipation capability; determines survivability against common lightning-induced surges. |
| Leakage Current (IRM) | 0.2 µA at 25 °C - ultra-low standby loss critical for battery-backed or low-power sensor nodes. |
| Junction Temperature (Tj max) | +150 °C - enables operation in high-ambient environments like engine compartments or enclosed power converters. |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline per IPC 7531; supports automated placement and reflow per J-STD-020 MSL Level 1. |
Pinout & Package
SMAJ70A-TR uses the JEDEC DO-214AC (SMA) package: a two-terminal surface-mount device with cathode band marking. The package measures 4.80–5.35 mm (E) × 2.25–2.90 mm (D) × 0.75–1.50 mm (L), optimized for thermal dissipation on FR4 PCBs with 70 µm copper.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or lowest potential node; completes shunt path during transient events. |
| Cathode | Protected line input | Connected to the line being safeguarded (e.g., 24 V supply rail); carries full surge current during clamping. |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61000-4-2 ESD immunity | 30 kV contact/air discharge - exceeds Level 4, eliminating need for external ESD diodes in USB or CAN interface protection. |
| Low dynamic resistance | 3.75 Ω at 8/20 µs - minimizes voltage overshoot during fast transients, reducing stress on downstream 75 V-rated MOSFETs. |
| High-temperature reliability | Rated to +150 °C junction - maintains clamping stability in under-hood automotive modules without derating. |
| UL94 V0 flammability rating | Self-extinguishing epoxy housing - satisfies safety requirements for industrial equipment enclosures per IEC 62368-1. |
| Matte tin-plated leads | JESD 22-B102 E3 solderability - ensures robust wetting and joint integrity during lead-free reflow (260 °C, 10 s). |
Applications
| Industrial PLC I/O Protection | Automotive Body Control Module |
|---|---|
|
Use Scenario: 24 V DC input channel on programmable logic controller exposed to load dump and inductive switching noise. IC Role / Device Role: Unidirectional shunt TVS placed between input rail and chassis ground. Use Value: Clamps 400 W surges to ≤113 V, protecting 3.3 V/5 V level translators and isolated RS-485 transceivers from permanent damage. |
Use Scenario: LIN bus line in door module subjected to ESD events during assembly and field service. IC Role / Device Role: Low-capacitance TVS on LIN data line referenced to vehicle ground. Use Value: 0.2 µA leakage preserves bus idle voltage; 30 kV ESD rating prevents latch-up in LIN transceivers without signal distortion. |
| Telecom Power Supply Input | Smart Meter AC/DC Auxiliary Rail |
|
Use Scenario: Primary-side 48 V DC input to telecom power converter encountering lightning-induced surges on outdoor cabling. IC Role / Device Role: First-stage TVS on bulk input rail upstream of DC-DC controller. Use Value: 113 V clamping provides ≥20% margin over 48 V nominal, enabling use with standard 100 V MOSFETs in primary switch stage. |
Use Scenario: 12 V auxiliary rail derived from mains-powered SMPS in utility smart meter, subject to conducted surges per IEC 61000-4-4. IC Role / Device Role: Secondary-side TVS protecting real-time clock and metrology IC power pins. Use Value: 400 W rating handles repetitive 2 kV/10/1000 µs surges; +150 °C Tj rating ensures reliability in sealed, thermally constrained meter housings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ70CA-TR | Bidirectional configuration; symmetric clamping (±113 V); higher capacitance due to dual-junction structure. | Required for AC-coupled or differential signal lines (e.g., RS-485, CAN FD) where polarity reversal occurs. | Select only if bidirectional protection is mandated; otherwise SMAJ70A-TR offers lower leakage and better DC rail efficiency. |
| SMBJ70A | Same VRM/VBR/VCL specs but SMB (DO-214AA) package; 600 W PPP rating; larger footprint (5.28 mm × 4.60 mm). | Used where higher surge energy handling is needed and board space permits larger package. | Choose when system-level testing requires >400 W margin; avoid if PCB layout is constrained to SMA footprints. |
Compared with SMAJ70CA-TR, SMAJ70A-TR delivers 50% lower leakage for DC-biased rails; versus SMBJ70A, it saves 35% board area while maintaining identical electrical protection thresholds - making it optimal for space-constrained industrial controllers.
Availability
SMAJ70A-TR is available at Aetrix Electronics and suitable for industrial PLC I/O protection, automotive body control modules, telecom power supply inputs, and smart meter auxiliary rails requiring stable component supply across multi-year production cycles.
Supply support for SMAJ70A-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, specializing in power management, analog, MEMS, and microcontroller technologies for industrial, automotive, and consumer markets.
SMAJ series TVS diodes belong to ST's circuit protection product line, engineered specifically for high-reliability transient suppression in harsh electromagnetic environments - emphasizing low leakage, high-temperature stability, and international EMC standard compliance.
FAQ
What is the maximum surge current SMAJ70A-TR can handle at 8/20 µs?
The device sustains 146 A peak pulse current at 8/20 µs waveform with a clamping voltage of 113 V, corresponding to its 2.3 kW peak pulse power rating. This value is verified per IEC 61000-4-5 test conditions and assumes proper PCB copper pour for thermal dissipation.
Does SMAJ70A-TR require derating at elevated ambient temperatures?
Yes - its peak pulse power must be linearly derated above 75 °C ambient: at 125 °C, maximum PPP drops to ~240 W (60% of 400 W). Derating follows the curve in Figure 3 of DS1251 Rev 15, based on junction-to-ambient thermal resistance of 4.5 °C/W on standard IPC 7531 footprint.
Can SMAJ70A-TR be used in parallel for higher surge capacity?
No - TVS diodes exhibit parametric spread in breakdown voltage (±5% typical), causing uneven current sharing. Parallel connection risks thermal runaway in the unit with lowest VBR. For higher energy handling, select a single higher-rated device like SMBJ70A or use staged protection with MOV + TVS.
Is the SMAJ70A-TR RoHS and REACH compliant?
Yes - it carries STMicroelectronics' ECOPACK2 environmental grade certification, meeting RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. Lead finish is matte tin, and packaging complies with J-STD-020 MSL Level 1 for moisture sensitivity.
SMAJ70A-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):
- 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)
SMAJ70A-TR FAQ
1.How can I place an order for SMAJ70A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70A-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 SMAJ70A-TR reliable?
The price and inventory of SMAJ70A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70A-TR is usually 5 days.
3.What payment methods are accepted for SMAJ70A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70A-TR?
SMAJ70A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70A-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 SMAJ70A-TR?
For technical support, including SMAJ70A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70A-TR requirements.
6.How does Aetrix verify that SMAJ70A-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ70A-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 SMAJ70A-TR meets industry standards.
7.What is the process for return or replacement of SMAJ70A-TR?
All SMAJ70A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70A-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 SMAJ70A-TR part is unused and in its original packaging.
Return procedure for SMAJ70A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ70A-TR Tags
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