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STMicroelectronics SMBJ20A-TR
- Part No.:
- SMBJ20A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ20A-TR.pdf
- Description:
- TVS DIODE 20VWM 32.4VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:11,618
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Product details
Overview
SMBJ20A-TR from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for primary-level surge protection on DC power rails and signal lines. It features a 20 V standoff voltage (VRM), 32.4 V clamping voltage at 19.4 A (10/1000 µs), 600 W peak pulse power rating, and operates up to 150 °C junction temperature-deployed in industrial power supplies and automotive body control modules to safeguard MOSFETs and microcontrollers against IEC 61000-4-4 level 4 surges.
For engineers reviewing the SMBJ20A-TR datasheet, SMBJ20A-TR pinout, SMBJ20A-TR application, or SMBJ20A-TR equivalent, key selection criteria include verified clamping performance at 19.4 A, low leakage (0.2 µA @ 25 °C), UL497B recognition (E136224), and SMB package compatibility with IPC7531 footprints-critical for ESD-hardened 24 V system designs.
Technical Context
This TVS diode uses planar silicon technology to achieve stable breakdown behavior and low dynamic resistance (0.404 Ω at 10/1000 µs), enabling precise voltage clamping during fast transients. Its unidirectional configuration provides asymmetric protection-forward conduction only during reverse overvoltage events-making it suitable for DC-biased lines where polarity is fixed.
The device meets IEC 61000-4-2 (30 kV air/contact discharge) and IEC 61000-4-4 (4 kV, 5/50 ns) immunity standards, with thermal performance validated up to 150 °C junction temperature and solderability certified per J-STD-002 and MIL-STD-750 method 2026.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 20 V - Maximum continuous reverse operating voltage before clamping initiates |
| Breakdown Voltage (VBR) | 22.2–23.4 V @ 1 mA - Confirmed avalanche onset range under controlled DC test conditions |
| Clamping Voltage (VCL) | 32.4 V @ 19.4 A (10/1000 µs) - Measured peak voltage limiting during standardized surge event |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - Sustained energy absorption capability at 25 °C ambient |
| Leakage Current (IRM) | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Low reverse bias current ensuring minimal standby power loss |
| Junction Temperature Range | −55 to +150 °C - Validated operational envelope for under-hood and industrial environments |
| UL Recognition | UL497B (E136224) - Certified as isolated loop circuit protector for telecom and industrial interfaces |
Pinout & Package
Package: SMB (DO-214AA), JEDEC-registered outline, 3.3–3.95 mm width × 5.1–5.6 mm length × 2.45 mm height, matte tin-plated leads compliant with JESD 22-B102 E3 and IPC7531 footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Marked Band) | Surge Current Sink | Connected to protected line; conducts transient energy to ground when reverse voltage exceeds VRM |
| Anode | Reference Node | Tied to system ground or lower-potential rail; completes clamping path during overvoltage events |
Key Features
| Feature | Design Value |
|---|---|
| High Surge Robustness | Withstands 600 W (10/1000 µs) and 4 kW (8/20 µs) pulses without degradation-enables single-device protection for 24 V industrial bus lines |
| Low Clamping Ratio | VCL/VBR = 32.4/22.2 ≈ 1.46 - Tight voltage margin ensures downstream ICs remain below absolute maximum ratings during transients |
| Thermal Stability | Rated for 150 °C operation with αT = 9.4 × 10⁻⁴/°C - Predictable VBR drift enables reliable design across extended temperature ranges |
| ESD Immunity | Exceeds IEC 61000-4-2 level 4 (30 kV contact/air) - Eliminates need for secondary ESD components on front-end interfaces |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
|
Use Scenario: 24 V DC input channel exposed to load dump and inductive switching noise in programmable logic controller backplanes. IC Role / Device Role / Timing Role: Primary surge clamp on power entry point, placed upstream of DC-DC converter and isolation barrier. Use Value: Limits transient voltage to ≤32.4 V at 19.4 A, preventing latch-up in downstream 3.3 V MCU and analog front-end ICs. |
Use Scenario: LIN bus transceiver power rail subject to battery reverse connection and jump-start surges. IC Role / Device Role / Timing Role: Unidirectional TVS on VCC line of LIN PHY, referenced to chassis ground. Use Value: Clamps 12 V rail transients within 1 ns response time, maintaining LIN signal integrity during ISO 16750-2 pulse 5a events. |
| Telecom Power Feeding Interface | Medical Patient Monitor Input |
|
Use Scenario: −48 V DC feeding port on remote radio unit exposed to lightning-induced surges on outdoor cabling. IC Role / Device Role / Timing Role: First-stage protection element on power input, coordinated with upstream GDT and downstream MOV. Use Value: Provides low-leakage (0.2 µA), high-clamping-accuracy protection compatible with UL497B isolated loop requirements. |
Use Scenario: 5 V USB-powered patient monitor sensor interface subjected to ESD during clinical handling. IC Role / Device Role / Timing Role: Point-of-entry TVS on VBUS line, placed adjacent to USB connector per IEC 61000-4-2 layout guidelines. Use Value: Absorbs 30 kV contact discharge without failure, preserving USB enumeration and data transfer reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ20CA-TR | Bidirectional variant; symmetric clamping (±32.4 V); higher capacitance (≈100 pF @ 1 V) | Required for AC-coupled or dual-polarity signal lines (e.g., RS-485, CAN FD) | Select only if bidirectional protection is mandated by signal topology-not drop-in for DC rails |
| SMCJ20A-TR | Same electrical specs but in larger SMC (DO-214AB) package; 1500 W (10/1000 µs) rating | Used where higher surge margin or board-level derating is required (e.g., outdoor power converters) | Choose when PCB layout allows larger footprint and >600 W headroom is needed for long-life field reliability |
Compared with SMBJ20CA-TR and SMCJ20A-TR, SMBJ20A-TR delivers optimal balance of compact SMB footprint, verified 600 W surge capacity, and ultra-low leakage-making it the preferred choice for space-constrained 24 V DC systems requiring UL497B compliance without over-engineering.
Availability
SMBJ20A-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, telecom power feeding interfaces, and medical patient monitor inputs requiring stable component supply and full traceability.
Supply support for SMBJ20A-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 robust, low-leakage DC rail protection in harsh environments-targeting applications demanding UL497B certification and high-temperature reliability.
FAQ
What is the maximum clamping voltage of SMBJ20A-TR at 19.4 A?
The maximum clamping voltage (VCL) is 32.4 V under 10/1000 µs waveform conditions at 25 °C ambient, measured per IEC 61000-4-5. This value increases with junction temperature at a coefficient of 9.4 × 10⁻⁴/°C, reaching ~34.1 V at 125 °C junction temperature.
Does SMBJ20A-TR meet UL497B requirements for isolated loop circuits?
Yes-SMBJ20A-TR is officially recognized under UL497B as an isolated loop circuit protector with agency file number E136224. This certification validates its use in telecom and industrial interfaces where galvanic isolation and surge withstand are mandated.
Can SMBJ20A-TR be used in bidirectional signal lines like RS-485?
No-SMBJ20A-TR is unidirectional and only clamps reverse-biased transients. For RS-485 or other AC-coupled differential buses, the bidirectional SMBJ20CA-TR must be used to protect both polarities equally.
What is the recommended PCB footprint for SMBJ20A-TR?
The JEDEC-standard SMB (DO-214AA) footprint per IPC7531 requires pad dimensions of 1.62 mm × 2.60 mm (anode) and 1.62 mm × 5.84 mm (cathode), with 2.07 mm center-to-center spacing. Copper area under each lead should exceed 1 cm² to maintain Rth(j-a) ≤ 120 °C/W per Figure 12.
SMBJ20A-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):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 19.4A
- 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
SMBJ20A-TR FAQ
1.How can I place an order for SMBJ20A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ20A-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 SMBJ20A-TR reliable?
The price and inventory of SMBJ20A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ20A-TR is usually 5 days.
3.What payment methods are accepted for SMBJ20A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ20A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ20A-TR?
SMBJ20A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ20A-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 SMBJ20A-TR?
For technical support, including SMBJ20A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ20A-TR requirements.
6.How does Aetrix verify that SMBJ20A-TR is sourced from the original manufacturer or authorized distributors?
All SMBJ20A-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 SMBJ20A-TR meets industry standards.
7.What is the process for return or replacement of SMBJ20A-TR?
All SMBJ20A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ20A-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 SMBJ20A-TR part is unused and in its original packaging.
Return procedure for SMBJ20A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ20A-TR Tags
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