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STMicroelectronics SMBJ85A-TR
- Part No.:
- SMBJ85A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ85A-TR.pdf
- Description:
- TVS DIODE 85VWM 137VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:9,069
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Product details
Overview
SMBJ85A-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 85 V stand-off voltage (VRM), 137 V clamping voltage (VCL) at 4.6 A (10/1000 µs), 600 W peak pulse power rating, and operates up to 150 °C junction temperature-used in industrial power supplies and telecom interface protection.
For engineers reviewing the SMBJ85A-TR datasheet, SMBJ85A-TR pinout, SMBJ85A-TR application, or SMBJ85A-TR equivalent, key selection criteria include clamping performance under IEC 61000-4-4 level 4 (4 kV), low leakage (<0.2 µA @ 25 °C), UL497B recognition (E136224), and SMB package compatibility with IPC7531 footprint.
Technical Context
This TVS diode employs planar silicon junction technology optimized for fast response (<1 ns) and stable clamping across temperature. Its unidirectional configuration provides asymmetric protection-blocking reverse conduction while clamping positive transients above VRM = 85 V.
It meets IEC 61000-4-2 (30 kV contact/air discharge) and IEC 61000-4-4 (4 kV, 50 Ω source) immunity standards, with dynamic resistance RD = 7.18 Ω enabling predictable voltage rise under surge current. Thermal design leverages SMB package's Rth(j-a) < 140 °C/W on standard FR4 PCBs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 85 V - maximum continuous reverse operating voltage before clamping initiates |
| Clamping Voltage (VCL) | 137 V at 4.6 A (10/1000 µs) - limits transient voltage seen by downstream ICs or MOSFETs |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - sustains single high-energy surges without failure |
| Leakage Current (IRM) | 0.2 µA @ 25 °C - negligible standby power loss in battery-powered or high-impedance circuits |
| Junction Temperature (Tj max) | 150 °C - enables reliable operation in enclosed industrial enclosures or near heat sources |
| Dynamic Resistance (RD) | 7.18 Ω - determines voltage overshoot slope during surge; lower RD improves clamping linearity |
| ESD Rating | 30 kV contact & air (IEC 61000-4-2 level 4) - protects against human-body-model ESD events |
Pinout & Package
Package: SMB (DO-214AA), surface-mount, JEDEC-registered outline with matte tin-plated leads compliant with J-STD-002 and JESD 22-B102 E3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Marked Band) | Surge current sink node | Connected to protected line; conducts during overvoltage to shunt energy to ground |
| Anode | Reference/return path | Typically tied to system ground or low-impedance return plane for effective clamping |
Key Features
| Feature | Design Value |
|---|---|
| UL497B Recognition | Approved as isolated loop circuit protector (File E136224) - enables use in safety-critical telecom and industrial isolation barriers |
| Low-Temperature Leakage Stability | IR ≤ 1 µA @ 85 °C - ensures minimal bias error drift in precision analog front-ends |
| High-Temperature Power Derating | 350 W sustained at Tj = 150 °C (10/1000 µs) - supports compact thermal design without external heatsinking |
| Robust Solderability | MSL Level 1, 260 °C lead temperature tolerance - compatible with standard reflow profiles per J-STD-020 |
| Controlled Capacitance | ~12 pF @ 0 V (typical, f = 1 MHz) - preserves signal integrity on 10–100 Mbps data lines (e.g., RS-485, CAN) |
Applications
| Industrial Power Supply Input Protection | Telecom Line Interface Protection |
|---|---|
|
Use Scenario: 24–48 V DC input stage of programmable logic controllers (PLCs) exposed to inductive switching and lightning-induced surges. IC Role / Device Role: Primary overvoltage clamp placed upstream of DC-DC converters and input EMI filters. Use Value: Limits transients to ≤137 V, preventing damage to 60 V-rated input MOSFETs and reducing need for oversized input capacitors. |
Use Scenario: RS-485 transceiver bus lines in outdoor base stations subject to ESD and induced surges. IC Role / Device Role: Point-of-entry protection on differential pair, referenced to local ground. Use Value: Clamps 4 kV IEC 61000-4-4 surges within 1 ns while adding <12 pF capacitance-no data rate degradation at 10 Mbps. |
| Automotive Body Control Module (BCM) Power Rail | Smart Meter AC/DC Auxiliary Supply |
|
Use Scenario: 12 V battery-supplied microcontroller power rail in BCMs subjected to load dump and ISO 7637-2 pulses. IC Role / Device Role: Secondary clamping device after primary TVS or varistor, fine-tuning voltage margin. Use Value: Provides precise 85 V VRM threshold aligned with automotive 12 V system nominal range, avoiding false triggering during cranking dips. |
Use Scenario: Auxiliary 5 V supply derived from mains via flyback converter in utility smart meters. IC Role / Device Role: Output-side transient suppressor protecting metering SoC and real-time clock circuitry. Use Value: Maintains <0.2 µA leakage at 25 °C and <1 µA at 85 °C-critical for battery backup runtime and long-term calibration stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ85CA-TR | Bidirectional version; symmetrical clamping (±137 V); higher capacitance (~24 pF) | Required for AC-coupled or bidirectional signal lines (e.g., USB D+/D−, Ethernet PHY) | Select when protecting balanced or AC-signaled paths where polarity reversal may occur |
| SAC85-01ETG | Same VRM (85 V), but lower PPP (400 W), higher RD (12.5 Ω), and smaller SOD-123FL package | Limited to lower-energy surges; unsuitable for IEC 61000-4-4 level 4 compliance | Choose only for space-constrained designs with verified sub-400 W surge requirements |
Compared with SMBJ85CA-TR, SMBJ85A-TR offers tighter clamping control for DC-biased rails and lower parasitic capacitance; versus SAC85-01ETG, it delivers 50% higher surge energy handling and proven UL497B qualification for safety-critical deployments.
Availability
SMBJ85A-TR is available at Aetrix Electronics and suitable for industrial power supplies, telecom interface protection, automotive body control modules, and smart meter auxiliary supplies requiring stable component supply and long-term lifecycle support.
Supply support for SMBJ85A-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 specializing in power management, analog, MEMS, and microcontrollers-with broad industrial, automotive, and consumer product portfolios.
The SMBJ series belongs to ST's high-reliability TVS diode family, engineered specifically for robust surge immunity in harsh environments-emphasizing low leakage, high-temperature stability, and regulatory compliance (UL, IEC, AEC-Q200).
FAQ
What is the maximum surge current SMBJ85A-TR can handle at 10/1000 µs?
The SMBJ85A-TR withstands 4.6 A peak pulse current at its specified 137 V clamping voltage under 10/1000 µs waveform. At lower clamping voltages (e.g., 120 V), it supports up to ~5.5 A, per the VCL–IPP curve in Figure 5 of DS1283 Rev 14. Derating applies above 25 °C ambient.
Does SMBJ85A-TR meet automotive qualification standards?
SMBJ85A-TR is not AEC-Q200 qualified. It is rated for industrial and telecom use with Tj max = 150 °C and UL497B recognition. For automotive applications, ST recommends the AEC-Q200-qualified SMAJ85A or 1.5SMC85A series-both share identical electrical specs but undergo extended reliability testing.
How does SMBJ85A-TR differ from SMBJ85CA-TR in layout and routing?
SMBJ85A-TR has polarity-sensitive placement: cathode (banded end) must connect to the protected line, anode to ground. SMBJ85CA-TR is bidirectional and symmetric-either terminal may serve as input or return-simplifying routing on differential or AC-coupled traces but requiring higher board capacitance margin.
Can SMBJ85A-TR be used in parallel for higher surge capacity?
No-parallel connection is not recommended due to mismatched dynamic resistance (RD = 7.18 Ω) and VBR tolerances (±5%). Uneven current sharing risks thermal runaway. For >600 W protection, use a single higher-power device like 5.0SMDJ85A (5 kW) or cascade stages with impedance-matched resistors.
SMBJ85A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJ, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 85V
- Voltage - Breakdown (Min):
- 94V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 4.6A
- 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
SMBJ85A-TR FAQ
1.How can I place an order for SMBJ85A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ85A-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 SMBJ85A-TR reliable?
The price and inventory of SMBJ85A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ85A-TR is usually 5 days.
3.What payment methods are accepted for SMBJ85A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ85A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ85A-TR?
SMBJ85A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ85A-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 SMBJ85A-TR?
For technical support, including SMBJ85A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ85A-TR requirements.
6.How does Aetrix verify that SMBJ85A-TR is sourced from the original manufacturer or authorized distributors?
All SMBJ85A-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 SMBJ85A-TR meets industry standards.
7.What is the process for return or replacement of SMBJ85A-TR?
All SMBJ85A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ85A-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 SMBJ85A-TR part is unused and in its original packaging.
Return procedure for SMBJ85A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ85A-TR Tags
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