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STMicroelectronics SMBJ28A-TR
- Part No.:
- SMBJ28A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ28A-TR.pdf
- Description:
- TVS DIODE 28VWM 45.4VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:10,152
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Product details
Overview
SMBJ28A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode in SMB package, designed for robust ESD and surge protection of sensitive signal/power lines. It features a 28 V stand-off voltage (VRM), 31.1–32.7 V breakdown voltage (VBR) at 1 mA, 45.4 V clamping voltage (VCL) at 13.8 A (10/1000 µs), 600 W peak pulse power rating, and operates up to 150 °C junction temperature - deployed in industrial power supplies, automotive body control modules, and industrial I/O interfaces.
For engineers reviewing the SMBJ28A-TR datasheet, SMBJ28A-TR pinout, SMBJ28A-TR application, or SMBJ28A-TR equivalent, key selection criteria include clamping performance under 10/1000 µs surges, low leakage (<0.2 µA @ 25 °C), UL497B recognition for isolated loop protection, and compatibility with IPC7531 footprint and JEDEC SMB outline.
Technical Context
This TVS diode uses planar silicon technology to achieve low leakage current and stable clamping across temperature (αT = 9.8 × 10⁻⁴ /°C). Its unidirectional configuration provides asymmetric conduction: low forward voltage drop (~1.5 V @ 1 A) during fault conditions while maintaining high impedance in reverse bias until VBR is exceeded.
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 (RD) of 0.802 Ω enabling fast response (<1 ns) and precise voltage limiting. Thermal design leverages FR4 PCB copper area to manage Rth(j-a), supporting sustained operation at Tj = 150 °C with derated power (350 W).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 28 V - Maximum continuous reverse operating voltage before significant leakage begins. |
| Breakdown Voltage (VBR) | 31.1–32.7 V @ 1 mA - Confirmed threshold where avalanche conduction initiates reliably. |
| Clamping Voltage (VCL) | 45.4 V @ 13.8 A (10/1000 µs) - Peak voltage seen by protected circuit during standardized surge event. |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - Sustained surge energy handling capability at 25 °C ambient. |
| Leakage Current (IRM) | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Ensures minimal loading on high-impedance signal paths. |
| Junction Temperature Range | −55 to +150 °C - Enables deployment in under-hood automotive and industrial environments. |
| UL Recognition | UL497B (File E136224) - Certified for use as isolated loop circuit protector per safety standard. |
Pinout & Package
Package: SMB (DO-214AA), JEDEC registered outline, IPC7531 compliant footprint, matte tin-plated leads (MSL Level 1, J-STD-020).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Marked Band) | Surge Current Sink | Connected to protected line; conducts avalanche current to ground during overvoltage events. |
| Anode | Reference Node | Tied to system ground or lower-potential rail; completes conduction path during reverse-bias transients. |
Key Features
| Feature | Design Value |
|---|---|
| Low Clamping Ratio | VCL/VBR = 1.45 - Minimizes stress on downstream ICs during transient events. |
| High-Temperature Stability | αT = 9.8 × 10⁻⁴ /°C - Predictable VBR and VCL drift ensures consistent protection across operating range. |
| ESD Robustness | ±30 kV contact/air (IEC 61000-4-2) - Exceeds level 4 requirements for human-body model immunity. |
| Lead-Free & RoHS Compliant | ECOPACK2 grade - Meets environmental compliance without compromising solderability or thermal performance. |
| Fast Response Time | <1 ns - Limits voltage overshoot before protection engages, critical for high-speed data lines. |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module (BCM) |
|---|---|
|
Use Scenario: Input rectifier output and DC bus lines exposed to load dump and inductive switching transients. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between +12 V rail and chassis ground to limit surge-induced overvoltage. Use Value: Clamps 45.4 V at 13.8 A, preventing damage to downstream PMICs and microcontrollers rated for ≤40 V absolute maximum. |
Use Scenario: LIN bus transceiver pins and sensor supply lines subject to ESD and battery reversal pulses. IC Role / Device Role / Timing Role: Standoff-rated TVS protecting LIN PHY inputs against ±30 kV ESD and 100 V/50 ms load dump. Use Value: Low leakage (0.2 µA @ 25 °C) avoids signal integrity degradation on 19.2 kbps bidirectional bus. |
| Programmable Logic Controller (PLC) I/O Modules | Industrial Ethernet PHY Interface |
|
Use Scenario: 24 V digital input channels interfacing with field sensors prone to wiring-induced surges. IC Role / Device Role / Timing Role: Primary overvoltage clamp on optocoupler input side, coordinated with series current-limiting resistor. Use Value: 600 W peak power rating handles repetitive 10/1000 µs transients per IEC 61000-4-4, ensuring long-term reliability. |
Use Scenario: RJ45 magnetics secondary side and PHY VDDIO lines vulnerable to ESD coupling via cable. IC Role / Device Role / Timing Role: Secondary-level TVS on MDI differential pairs and power rails, supplementing primary front-end protection. Use Value: UL497B recognition validates safe use in isolated communication circuits with reinforced insulation barriers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ28CA-TR | Bidirectional version; symmetric clamping (VCL = 45.4 V in both polarities); same VRM, VBR, and PPP ratings. | Required for AC-coupled or floating signal lines (e.g., RS-485, CAN FD) where polarity reversal occurs. | Select when protecting bidirectional data buses or transformer-coupled interfaces needing symmetrical surge suppression. |
| SMAJ28A | Lower PPP rating (400 W vs. 600 W); larger SMA package (DO-214AC); higher RD (1.08 Ω); identical VBR/VCL specs. | Suitable for space-constrained but lower-energy surge environments (e.g., consumer-grade peripherals). | Choose only if board layout allows SMA footprint and application surge energy remains below 400 W (10/1000 µs). |
Compared with SMBJ28CA-TR and SMAJ28A, SMBJ28A-TR delivers optimal balance of high-power surge handling, compact SMB form factor, and unidirectional precision - making it preferred for DC-powered industrial and automotive subsystems where polarity is fixed and energy levels exceed 400 W.
Availability
SMBJ28A-TR is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and programmable logic controller I/O modules requiring stable component supply, long-lifecycle support, and certified surge protection.
Supply support for SMBJ28A-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.
The SMBJ series belongs to ST's transient protection portfolio, engineered specifically for high-reliability DC line protection in harsh environments - emphasizing low leakage, high-temperature stability, and standards-compliant surge resilience.
FAQ
What is the maximum clamping voltage of SMBJ28A-TR under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 45.4 V at 13.8 A for a 10/1000 µs waveform, measured at 25 °C ambient. This value increases with junction temperature at a rate defined by αT = 9.8 × 10⁻⁴ /°C, reaching ~48.2 V at Tj = 125 °C.
Is SMBJ28A-TR suitable for protecting CAN bus lines?
No - SMBJ28A-TR is unidirectional and not rated for CAN bus signaling. CAN requires bidirectional protection (e.g., SMBJ28CA-TR) to handle differential voltage swings and recessive-dominant transitions without forward conduction on either line.
Does SMBJ28A-TR meet automotive qualification standards?
While not AEC-Q200 qualified, SMBJ28A-TR meets IEC 61000-4-2/4-4, UL497B, and operates up to 150 °C junction temperature - enabling use in non-safety-critical automotive subsystems like body electronics when validated per OEM-specific test plans.
How does the SMB package compare to SMA in thermal performance?
The SMB package offers lower thermal resistance than SMA due to wider lead spacing and optimized copper pad layout (Rth(j-a) ≈ 120 °C/W on 1 cm² Cu vs. ~150 °C/W for SMA), enabling higher sustained power dissipation - especially critical for repeated surge events in industrial SMPS designs.
SMBJ28A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJ, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 13.8A
- Power - Peak Pulse:
- 600W
- 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:
- SMB
SMBJ28A-TR FAQ
1.How can I place an order for SMBJ28A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ28A-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 SMBJ28A-TR reliable?
The price and inventory of SMBJ28A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ28A-TR is usually 5 days.
3.What payment methods are accepted for SMBJ28A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ28A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ28A-TR?
SMBJ28A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ28A-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 SMBJ28A-TR?
For technical support, including SMBJ28A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ28A-TR requirements.
6.How does Aetrix verify that SMBJ28A-TR is sourced from the original manufacturer or authorized distributors?
All SMBJ28A-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 SMBJ28A-TR meets industry standards.
7.What is the process for return or replacement of SMBJ28A-TR?
All SMBJ28A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ28A-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 SMBJ28A-TR part is unused and in its original packaging.
Return procedure for SMBJ28A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ28A-TR Tags
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