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Taiwan Semiconductor Corporation SMBJ18
- Part No.:
- SMBJ18
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ18.pdf
- Description:
- 600W, 22.2V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:4,618
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Product details
Overview
SMBJ18 from Taiwan Semiconductor is a unidirectional 600W surface-mount transient voltage suppressor (TVS) diode in DO-214AA (SMB) package, designed for high-energy surge protection in DC power rails and signal lines. It features a 18 V working stand-off voltage (VWM), 20.0–24.4 V breakdown voltage (VBR @ 1 mA), 32.2 V maximum clamping voltage (VC) at 19.5 A peak pulse current, and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive electronics.
For engineers reviewing the SMBJ18 datasheet, SMBJ18 pinout, SMBJ18 application, or SMBJ18 equivalent, key selection criteria include clamping performance under 10/1000 µs transients, leakage current ≤1 µA at 18 V, thermal derating above 25°C, and compatibility with automated SMT placement on industrial control and automotive ECUs.
Technical Context
The SMBJ18 operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its breakdown threshold (20.0–24.4 V), diverting surge current to ground while clamping the protected line to ≤32.2 V. Its glass-passivated junction ensures stable VBR and low leakage (<1 µA at VWM).
Thermal design relies on RθJA = 55°C/W and RθJC = 10°C/W, enabling sustained operation up to TJ = 150°C. It supports single 8.3 ms half-sine surge currents up to 100 A (IFSM) and complies with JESD201 Class 2 whisker resistance and J-STD-020 Moisture Sensitivity Level 1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before conduction begins |
| VBR min/max | 20.0 / 24.4 V @ 1 mA - Confirmed avalanche onset range under standardized test conditions |
| VC @ IPP | 32.2 V @ 19.5 A - Clamped voltage during 10/1000 µs surge, defining worst-case overvoltage seen by downstream circuitry |
| PPK | 600 W - Peak pulse power handling capability per single 10/1000 µs transient |
| ID @ VWM | <1 µA - Reverse leakage at rated stand-off, critical for low-power sensor and battery-backed circuits |
| TJ max | +150 °C - Maximum junction temperature, supporting operation in under-hood automotive environments |
| Package | DO-214AA (SMB) - Standardized surface-mount outline with 0.090 g mass and matte tin-plated leads |
Pinout & Package
DO-214AA (SMB) package: molded plastic case meeting UL 94V-0 flammability rating; cathode indicated by band marking; polarity-sensitive for unidirectional operation; terminals are solderable per J-STD-002.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to system ground or lowest potential node; completes conduction path during reverse surge |
| Cathode | Protected line connection | Connected to line being safeguarded (e.g., 12 V rail); blocks normal operation, conducts only during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| Clamping performance | 32.2 V VC at 19.5 A ensures robust protection of 24 V systems against ISO 7637-2 Pulse 2b (inductive load dump) |
| Response time | <1.0 ps enables suppression of ESD and fast transients before sensitive ICs experience overstress |
| Leakage control | <1 µA ID at 18 V preserves battery life in always-on automotive modules and IoT edge sensors |
| Automated assembly support | DO-214AA footprint and matte tin plating ensure reliable reflow soldering in high-volume SMT lines |
| Environmental compliance | RoHS-compliant and halogen-free per IEC 61249-2-21, suitable for green manufacturing programs |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 24 V supply inputs in engine control units (ECUs) and body control modules (BCMs) from load dump and alternator transients. IC Role / Device Role: Unidirectional TVS diode placed between power rail and chassis ground to clamp surges exceeding 18 V. Use Value: Limits voltage to ≤32.2 V during 10/1000 µs pulses, preventing damage to microcontrollers and CAN transceivers rated for 36 V absolute max. |
Use Scenario: Safeguarding analog input pins of precision ADCs in PLC analog I/O modules exposed to field wiring transients. IC Role / Device Role: Low-leakage (≤1 µA) TVS placed across signal and ground to absorb EFT bursts without loading the sensor output. Use Value: Maintains signal integrity during IEC 61000-4-4 EFT testing (±2 kV) while adding <0.1 pF parasitic capacitance at 0 V bias. |
| LED Driver Output Protection | DC Motor Control Board Protection |
Use Scenario: Shielding constant-current LED driver outputs from inductive kickback when driving long cable runs or high-power arrays. IC Role / Device Role: Unidirectional TVS connected anode-to-ground, cathode-to-driver output to absorb reverse EMF spikes. Use Value: Withstands 600 W peak pulse energy and clamps to 32.2 V, preventing latch-up or gate oxide failure in MOSFET drivers. |
Use Scenario: Suppressing flyback voltage generated by brushed DC motors during PWM switching in robotics and HVAC actuators. IC Role / Device Role: TVS mounted across motor terminals to shunt inductive energy back into the H-bridge supply rail. Use Value: Fast <1 ps response captures initial voltage spike before MOSFET avalanche limits, reducing thermal stress on bridge FETs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18A | Narrower VBR range (20.0–22.1 V), lower clamping voltage (29.2 V @ 21.5 A), tighter tolerance | Better suited for designs requiring tighter voltage margin around 18 V nominal rails | Select SMBJ18A when clamping headroom below 30 V is mandatory; SMBJ18 offers higher surge current margin at same VWM |
| SMAJ18A | Lower PPK (400 W), smaller SMA package (DO-214AC), higher RθJA (75°C/W) | Limited to lower-energy transients; not recommended for ISO 7637-2 Pulse 2b or load dump | Choose SMAJ18A only for space-constrained consumer-grade applications where 400 W peak power suffices |
Compared with SMBJ18A, the SMBJ18 trades tighter VBR tolerance for higher surge current capacity (19.5 A vs. 21.5 A) and slightly higher clamping (32.2 V vs. 29.2 V); versus SMAJ18A, it delivers 50% more peak power in a thermally superior package but occupies larger PCB area.
Availability
SMBJ18 is available at Aetrix Electronics and suitable for automotive electronics, industrial control systems, and LED lighting applications requiring stable component supply, full traceability, and lifecycle continuity.
Supply support for SMBJ18 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs, headquartered in Hsinchu, Taiwan.
The SMBJ series was developed specifically for high-reliability transient suppression in automotive and industrial environments, emphasizing robust clamping, low leakage, and AEC-Q200-aligned reliability testing.
FAQ
What is the maximum clamping voltage of SMBJ18 under standard 10/1000 µs surge conditions?
The SMBJ18 has a maximum clamping voltage (VC) of 32.2 V when subjected to a 10/1000 µs waveform at its rated peak pulse current of 19.5 A. This value is measured per ANSI/IEEE C62.35 and defines the upper voltage limit imposed on protected circuitry during surge events. The SMBJ18 maintains this clamping performance across its specified operating temperature range.
Is SMBJ18 suitable for bidirectional transient protection?
No, SMBJ18 is a unidirectional TVS diode intended for DC line protection where polarity is fixed. For bidirectional applications such as AC lines or data bus protection, the SMBJ18C or SMBJ18CA variants must be used - these incorporate symmetrical breakdown characteristics in both directions. The SMBJ18 itself conducts only in reverse bias and blocks forward current like a standard rectifier.
What is the leakage current specification for SMBJ18 at its working stand-off voltage?
The SMBJ18 exhibits a maximum blocking leakage current (ID) of 1 µA when biased at its 18 V working stand-off voltage (VWM) and tested at 25°C. This low leakage ensures minimal power loss in battery-powered or energy-sensitive systems. Leakage remains within specification up to +125°C, with typical values well below 0.5 µA at room temperature.
Does SMBJ18 meet automotive transient immunity standards?
Yes, SMBJ18 meets ISO 7637-2 requirements for Pulse 1 (inductive load disconnect), Pulse 2a (sudden load removal), Pulse 2b (inductive switch-off), Pulse 3a (capacitive coupling), and Pulse 3b (supply line noise). Its 600 W peak power rating and sub-1 ps response enable compliance with these waveforms when properly mounted with low-inductance grounding paths.
What is the thermal resistance from junction to ambient for SMBJ18?
The SMBJ18 has a junction-to-ambient thermal resistance (RθJA) of 55°C/W under standard JEDEC test conditions (single device on 1-inch² FR-4 board with 2 oz copper). This value assumes no additional copper pour or heatsinking. For high-reliability designs, thermal derating per Figure 2 in the datasheet must be applied above 25°C ambient to maintain TJ ≤ 150°C.
SMBJ18 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJ
- 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:
- 32.2V
- Current - Peak Pulse (10/1000µs):
- 19.5A
- 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:
- DO-214AA (SMB)
SMBJ18 FAQ
1.How can I place an order for SMBJ18 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ18 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 SMBJ18 reliable?
The price and inventory of SMBJ18 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ18 is usually 5 days.
3.What payment methods are accepted for SMBJ18?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ18 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ18?
SMBJ18 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ18 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 SMBJ18?
For technical support, including SMBJ18 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ18 requirements.
6.How does Aetrix verify that SMBJ18 is sourced from the original manufacturer or authorized distributors?
All SMBJ18 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 SMBJ18 meets industry standards.
7.What is the process for return or replacement of SMBJ18?
All SMBJ18 units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ18, 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 SMBJ18 part is unused and in its original packaging.
Return procedure for SMBJ18:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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