My Inquiry
My Account
STMicroelectronics SMBJ18A-TR
- Part No.:
- SMBJ18A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ18A-TR.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:17,715
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SMBJ18A-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 18 V standoff voltage (VRM), 29.2 V clamping voltage at 21.5 A (10/1000 µs), 600 W peak pulse power rating, and operates up to 150 °C junction temperature-commonly deployed in industrial power supplies and automotive body control modules.
For engineers reviewing the SMBJ18A-TR datasheet, SMBJ18A-TR pinout, SMBJ18A-TR application, or SMBJ18A-TR equivalent, key selection criteria include clamping performance under IEC 61000-4-4 level 4 (4 kV), low leakage (<0.2 µA at 25 °C), UL497B recognition (E136224), and SMB package compatibility with IPC7531 footprints.
Technical Context
This TVS diode uses planar silicon technology to achieve stable breakdown behavior and low dynamic resistance (0.328 Ω at 25 °C), enabling precise voltage clamping during fast transients such as ESD (IEC 61000-4-2, ±30 kV contact/air) and inductive switching surges. Its unidirectional configuration provides asymmetric protection ideal for DC-biased lines.
The device complies with JEDEC registered SMB outline, J-STD-020 MSL Level 1, and UL497B recognition for isolated loop circuit protection. Thermal performance is validated up to 150 °C junction temperature, with derated pulse power reaching 350 W at Tj = 150 °C (10/1000 µs).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - Maximum continuous reverse operating voltage before conduction begins. |
| Breakdown Voltage (VBR min) | 20.0 V at 1 mA - Ensures reliable triggering above normal operating rail. |
| Clamping Voltage (VCL) | 29.2 V at 21.5 A (10/1000 µs) - Limits transient voltage seen by downstream ICs. |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs) - Sustains high-energy surges without failure in typical industrial environments. |
| Leakage Current (IRM) | 0.2 µA at 25 °C - Minimizes standby power loss in battery-backed or low-power systems. |
| Junction Temperature Range | −55 °C to +150 °C - Supports operation in under-hood automotive and industrial SMPS applications. |
| Dynamic Resistance (RD) | 0.328 Ω - Low impedance during clamping improves voltage regulation under surge current. |
Pinout & Package
The SMBJ18A-TR is housed in an SMB (DO-214AA) surface-mount package measuring 3.3–3.95 mm × 5.1–5.6 mm × 1.9–2.45 mm (L×W×H), with matte tin-plated leads compliant with J-STD-002 and MIL-STD-750 Method 2026.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Marked Band) | Surge Current Sink | Connected to protected line; conducts transient energy to ground when voltage exceeds VBR. |
| Anode | Reference Node | Tied to system ground or lower-potential rail; completes clamping path during overvoltage events. |
Key Features
| Feature | Design Value |
|---|---|
| UL497B Recognition | Agency file E136224 confirms suitability for isolated loop circuit protection in telecom and industrial interfaces. |
| ESD Robustness | Exceeds IEC 61000-4-2 level 4: ±30 kV air/contact discharge ensures reliability in handling and assembly environments. |
| Low-Temperature Leakage | 0.2 µA at 25 °C and 1 µA at 85 °C enables use in precision analog front-ends and sensor signal conditioning. |
| High-Temperature Derating | Maintains 350 W pulse capability at 150 °C junction temperature-critical for compact, thermally constrained power designs. |
| JEDEC-Compliant SMB Footprint | Validated IPC7531 land pattern ensures manufacturability and thermal reliability on FR4 PCBs with 70 µm copper. |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Protecting 24 V DC input stage of programmable logic controllers (PLCs) against load dump and inductive kickback. IC Role / Device Role / Timing Role: Primary clamping element placed upstream of DC-DC converters and microcontrollers. Use Value: Clamps 4 kV IEC 61000-4-4 surges to ≤29.2 V, preventing latch-up or gate oxide damage in downstream MOSFET drivers. | Use Scenario: Safeguarding LIN bus transceivers and window motor drivers from battery reverse polarity and jump-start transients. IC Role / Device Role / Timing Role: Unidirectional TVS on 12 V supply rail, coordinated with fuse and reverse-protection MOSFET. Use Value: Withstands 150 °C ambient under hood while maintaining <1 µA leakage-preserving sleep-mode current budgets. |
| Telecom Interface Surge Protection | Medical Equipment Input Stage |
Use Scenario: Front-end protection for PoE-powered Ethernet switches handling induced lightning surges on data lines. IC Role / Device Role / Timing Role: Secondary-level TVS after gas discharge tube (GDT), providing fast-response clamping for residual transients. Use Value: 0.328 Ω dynamic resistance ensures minimal overshoot during 8/20 µs surges up to 102 A, preserving signal integrity. | Use Scenario: Isolated DC power entry point in portable ultrasound devices requiring low EMI and patient-safety compliance. IC Role / Device Role / Timing Role: Standoff-rated TVS on auxiliary 5 V/3.3 V rails feeding ADC reference and clock circuits. Use Value: UL497B recognition supports regulatory approval for medical-grade isolated loop protection per IEC 60601-1. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18CA-TR | Bidirectional version; symmetric clamping (±29.2 V); higher capacitance (~200 pF @ 0 V). | Required for AC-coupled or dual-polarity signal lines (e.g., RS-485, CAN FD). | Select only if bidirectional protection is needed; not interchangeable in DC-biased circuits. |
| SMCJ18A-TR | Larger SMC package; 1500 W peak power (10/1000 µs); same VRM/VCL but higher IPP (42.1 A). | Used where higher surge margin is mandated (e.g., outdoor telecom cabinets, railway electronics). | Choose when board space allows and 1500 W rating is required; not drop-in due to footprint mismatch. |
Compared with SMBJ18CA-TR and SMCJ18A-TR, the SMBJ18A-TR offers optimal balance of compact SMB footprint, 600 W surge handling, and ultra-low leakage-making it preferred for space-constrained, low-power DC systems where unidirectional clamping suffices.
Availability
SMBJ18A-TR is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, telecom interface protection, and medical equipment input stages requiring stable component supply across extended production lifecycles.
Supply support for SMBJ18A-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 high-reliability applications demanding UL497B recognition and extended temperature operation.
FAQ
What is the maximum clamping voltage of SMBJ18A-TR under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 29.2 V at 21.5 A for a 10/1000 µs waveform, measured at 25 °C. This value increases with junction temperature per the αT coefficient (9.2 × 10⁻⁴/°C), reaching ~32.5 V at 125 °C junction temperature.
Does SMBJ18A-TR meet IEC 61000-4-2 and IEC 61000-4-4 immunity requirements?
Yes-it exceeds IEC 61000-4-2 level 4 (±30 kV air/contact discharge) and meets IEC 61000-4-4 level 4 (4 kV, 5/50 ns surge) when used with appropriate PCB layout and grounding. Its fast response time (<1 ns) and low dynamic resistance ensure effective suppression.
Is SMBJ18A-TR compatible with lead-free reflow soldering processes?
Yes-the device is qualified for lead-free reflow per J-STD-020 MSL Level 1, with a peak reflow temperature of 240–245 °C for ≤60 seconds. The matte tin plating meets JESD 22-B102 E3 and MIL-STD-750 Method 2026 solderability standards.
How does SMBJ18A-TR differ from SMBJ18CA-TR in circuit implementation?
SMBJ18A-TR is unidirectional and must be oriented with cathode toward the protected line; SMBJ18CA-TR is bidirectional and symmetrical, allowing placement without polarity concern. The latter exhibits higher junction capacitance (~200 pF vs. ~50 pF for SMBJ18A-TR), affecting high-speed signal lines.
SMBJ18A-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):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 21.5A
- 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
SMBJ18A-TR FAQ
1.How can I place an order for SMBJ18A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ18A-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 SMBJ18A-TR reliable?
The price and inventory of SMBJ18A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ18A-TR is usually 5 days.
3.What payment methods are accepted for SMBJ18A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ18A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ18A-TR?
SMBJ18A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ18A-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 SMBJ18A-TR?
For technical support, including SMBJ18A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ18A-TR requirements.
6.How does Aetrix verify that SMBJ18A-TR is sourced from the original manufacturer or authorized distributors?
All SMBJ18A-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 SMBJ18A-TR meets industry standards.
7.What is the process for return or replacement of SMBJ18A-TR?
All SMBJ18A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ18A-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 SMBJ18A-TR part is unused and in its original packaging.
Return procedure for SMBJ18A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ18A-TR Tags
-
ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
-
D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
-
DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
-
D5V0L1B2WS-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
