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STMicroelectronics SMAJ33A-TR
- Part No.:
- SMAJ33A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ33A-TR.pdf
- Description:
- TVS DIODE 33VWM 69.7VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:26,726
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Product details
Overview
SMAJ33A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for primary-level ESD and surge protection in DC power rails and signal lines. It features a 33 V standoff voltage (VRM), 53.3 V clamping voltage at 7.5 A (10/1000 µs), 400 W peak pulse power rating, and operates up to +150 °C junction temperature - deployed in industrial power supplies, automotive body control modules, and PoE-powered Ethernet interfaces.
For engineers reviewing the SMAJ33A-TR datasheet, SMAJ33A-TR pinout, SMAJ33A-TR application, or SMAJ33A-TR equivalent, key selection criteria include clamping performance under IEC 61000-4-2 (30 kV contact/air), low leakage (<0.2 µA @ 25 °C), JEDEC DO-214AC (SMA) package compatibility, and thermal stability across -55 °C to +150 °C operating range.
Technical Context
This TVS diode uses planar silicon junction technology to achieve low dynamic resistance (RD = 1.70 Ω) and stable breakdown behavior over temperature. Its unidirectional configuration enables asymmetric clamping - conducting only during reverse overvoltage events while maintaining high impedance in forward bias.
The device complies with IEC 61000-4-2 Level 4 (30 kV air/contact discharge) and IEC 61000-4-4 Level 4 (4 kV), with clamping voltage defined at both 10/1000 µs (53.3 V) and 8/20 µs (69.7 V) waveforms - supporting robust protection against fast transients and longer-duration surges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 33 V - maximum continuous reverse operating voltage before conduction begins; defines minimum system rail margin for reliable protection. |
| Breakdown Voltage (VBR min) | 36.7 V @ 1 mA - guaranteed conduction onset threshold; ensures predictable triggering above nominal rail voltage. |
| Clamping Voltage (VCL) | 53.3 V @ 7.5 A (10/1000 µs) - peak voltage seen by protected circuit during surge; limits stress on downstream ICs. |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs) - energy-handling capability for standard lightning/surge waveforms; sufficient for most board-level protection. |
| Leakage Current (IRM) | 0.2 µA @ 25 °C - ultra-low reverse leakage preserves battery life and avoids false triggers in high-impedance sensing paths. |
| Junction Temperature Range | -55 °C to +150 °C - supports operation in under-hood automotive, industrial enclosures, and thermally constrained PCB layouts. |
| Package | DO-214AC (SMA) - industry-standard surface-mount outline per IPC-7531; compatible with automated assembly and reflow profiles. |
Pinout & Package
Package: DO-214AC (SMA), single-ended unidirectional configuration with cathode band marking. Standard footprint per IPC-7531: 5.43 mm × 2.63 mm pad pitch, 1.40 mm pad width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (unmarked end) | Low-side reference terminal | Connected to ground or lowest potential node; completes conduction path during reverse overvoltage events. |
| Cathode (banded end) | Protected line interface | Connected to the line being protected (e.g., 3.3 V/5 V/12 V rail); blocks forward current, clamps reverse surges. |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61000-4-2 Level 4 compliance | 30 kV air/contact discharge immunity - eliminates need for external ESD staging in USB, CAN, or sensor interfaces. |
| Low dynamic resistance | 1.70 Ω - minimizes clamping voltage rise under high-current transients, improving protection margin for 3.3 V–24 V systems. |
| High-temperature reliability | 150 °C max junction temperature - enables use in engine control units, motor drives, and enclosed industrial controllers without derating. |
| JEDEC-registered footprint | DO-214AC (SMA) - ensures mechanical and thermal compatibility with existing layout libraries and reflow processes. |
Applications
| Industrial Power Supply Input | Automotive Body Control Module |
|---|---|
|
Use Scenario: 24 V DC input stage of programmable logic controller (PLC) power supply exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Primary surge clamp on main DC input rail, absorbing energy before it reaches DC/DC converter and microcontroller. Use Value: Clamps 53.3 V at 7.5 A (10/1000 µs), limiting stress on 36 V-rated input capacitors and enabling compact, cost-effective front-end design. |
Use Scenario: LIN bus transceiver power line in door module subjected to ESD events during connector mating/unmating. IC Role / Device Role / Timing Role: Localized ESD suppressor on VCC rail adjacent to LIN PHY IC, placed within 2 mm of connector. Use Value: Sub-0.2 µA leakage prevents quiescent current increase; 30 kV contact discharge rating meets OEM ESD test requirements without additional filtering. |
| POE-Powered Ethernet Switch | Smart Sensor Node Interface |
|
Use Scenario: 48 V DC input of IEEE 802.3af/at powered device (PD) receiving power over Ethernet cabling. IC Role / Device Role / Timing Role: First-line transient protector on PD midspan input, coordinated with upstream MOV and secondary TVS stages. Use Value: 400 W pulse rating handles induced surges from cable coupling; DO-214AC package allows dense placement near RJ45 magnetics. |
Use Scenario: 3.3 V analog sensor supply rail in wireless environmental monitor exposed to field ESD during maintenance. IC Role / Device Role / Timing Role: Low-leakage TVS on precision ADC reference rail, protecting against human-body-model discharges. Use Value: 0.2 µA leakage avoids offset drift in 24-bit sigma-delta converters; 53.3 V clamping preserves headroom for 3.3 V LDO regulation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ33A from Vishay (SMAJ33A-E3/5AT) | Identical VRM (33 V), VBR (36.7 V min), and VCL (53.3 V), but higher IRM (1 µA @ 25 °C) and lower thermal robustness (Tj max = 125 °C). | Less suitable for high-temperature industrial deployments where long-term leakage stability is critical. | Select when cost sensitivity outweighs thermal margin requirements and leakage <0.5 µA is not mandatory. |
| 1.5SMC33A from ON Semiconductor | Same VRM and VCL, but larger SMC (DO-214AB) package (7.11 mm × 6.22 mm), 1.5 kW 8/20 µs rating, and higher RD (2.1 Ω). | Better suited for high-energy surge environments (e.g., AC mains input), but incompatible with space-constrained SMA footprints. | Choose only if board layout allows SMC footprint and system requires >400 W 10/1000 µs handling with no size constraint. |
Compared with SMAJ33A-TR, the Vishay part trades leakage and temperature capability for broader distribution, while the ON Semiconductor part offers higher surge capacity at the expense of PCB area and thermal efficiency - making SMAJ33A-TR optimal for compact, thermally demanding, low-leakage DC rail protection.
Availability
SMAJ33A-TR is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and PoE-powered devices requiring stable component supply, consistent parametric performance, and full traceability through STMicroelectronics' ECOPACK-compliant manufacturing chain.
Supply support for SMAJ33A-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 for automotive, industrial, and consumer markets.
The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for board-level ESD and surge immunity in space-constrained, high-reliability applications - emphasizing low leakage, thermal resilience, and JEDEC-standard packaging.
FAQ
What is the maximum clamping voltage of SMAJ33A-TR under IEC 61000-4-4 surge conditions?
The clamping voltage is 69.7 V at 6.2 A for the 8/20 µs waveform (IEC 61000-4-4 Level 4). This value is measured per DS1251 Rev 15, Table 2, and reflects worst-case voltage imposed on protected circuitry during fast-rising surges - critical for ensuring downstream ICs remain within absolute maximum ratings.
Can SMAJ33A-TR be used in bidirectional signal lines like RS-485?
No - SMAJ33A-TR is unidirectional and lacks symmetrical clamping. For RS-485 or other bidirectional data lines, SMAJ33CA (the complementary bidirectional variant) must be used instead, as it provides matched clamping in both polarities per Figure 8 and Table 2 of DS1251.
Does SMAJ33A-TR require derating at elevated ambient temperatures?
Yes - peak pulse power drops linearly with junction temperature: at 125 °C Tj, PPP is reduced to ~280 W (Figure 3, DS1251). Designers must apply thermal modeling using Rth(j-a) (Figure 12) and copper area to ensure Tj stays ≤150 °C under worst-case surge repetition and ambient conditions.
Is the SMAJ33A-TR RoHS and REACH compliant?
Yes - it carries STMicroelectronics' ECOPACK2 certification (lead-free, halogen-free, antimony-free), verified per DS1251 Rev 15 Section 2 and publicly documented at www.st.com/ecopack. The matte tin-plated leads meet J-STD-002 and JESD 22-B102 E3 standards for solderability and whisker resistance.
SMAJ33A-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):
- 33V
- Voltage - Breakdown (Min):
- 36.7V
- Voltage - Clamping (Max) @ Ipp:
- 69.7V
- Current - Peak Pulse (10/1000µs):
- 33A (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)
SMAJ33A-TR FAQ
1.How can I place an order for SMAJ33A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ33A-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 SMAJ33A-TR reliable?
The price and inventory of SMAJ33A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ33A-TR is usually 5 days.
3.What payment methods are accepted for SMAJ33A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ33A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ33A-TR?
SMAJ33A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ33A-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 SMAJ33A-TR?
For technical support, including SMAJ33A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ33A-TR requirements.
6.How does Aetrix verify that SMAJ33A-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ33A-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 SMAJ33A-TR meets industry standards.
7.What is the process for return or replacement of SMAJ33A-TR?
All SMAJ33A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ33A-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 SMAJ33A-TR part is unused and in its original packaging.
Return procedure for SMAJ33A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ33A-TR Tags
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