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Alpha & Omega Semiconductor Inc. SMDJ18A
- Part No.:
- SMDJ18A
- Manufacturer:
- Alpha & Omega Semiconductor Inc.
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMDJ18A.pdf
- Description:
- 1CH 18V UNIDIRECTIONAL 3000W SMD
- Quantity:
- Payment:
- Shipping:
Inventory:6,520
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Product details
Overview
SMDJ18A from Alpha & Omega Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy surge protection in DC power lines and signal interfaces. It features a 18.0 V reverse standoff voltage (VRWM), 20.0–22.1 V breakdown voltage (VBR) at 1 mA, 29.2 V maximum clamping voltage at 102.8 A peak pulse current, and 3000 W peak pulse power rating on 10/1000 µs waveform - deployed in industrial motor drives to protect gate drivers from IGBT switching transients.
For engineers reviewing the SMDJ18A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 10/1000 µs surges, thermal resistance (RθJL = 15 °C/W), unidirectional polarity with cathode band marking, DO-214AB package compatibility, and compliance with J-STD-020 MSL Level 1.
Technical Context
The SMDJ18A operates as a silicon avalanche diode optimized for fast transient suppression. Its glass-passivated junction enables sub-1 ps response time from 0 V to breakdown, while its low-profile DO-214AB (SMC J-Bend) package supports high-density PCB layouts and meets UL 94V-0 flammability requirements.
It delivers 3000 W peak pulse power handling with 0.01% duty cycle repetition rate, rated for -55 °C to +150 °C junction temperature, and exhibits a typical temperature coefficient of ΔVBR = 0.1% × VBR @ 25 °C × ΔT - ensuring stable clamping across operating temperature ranges in automotive body control modules.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18.0 V - Maximum continuous reverse working voltage before clamping begins; sets DC bus protection threshold. |
| VBR @ IT=1 mA | 20.0–22.1 V - Confirmed breakdown range ensures reliable turn-on during ESD/EFT events without premature conduction. |
| Vc @ IPPM | 29.2 V - Clamping voltage at 102.8 A peak pulse current; defines worst-case overvoltage seen by protected ICs. |
| PPPM (10/1000 µs) | 3000 W - Peak surge energy absorption capacity; enables protection against IEC 61000-4-5 Level 4 surges. |
| TJ max | +150 °C - Maximum junction temperature; supports operation in under-hood automotive environments. |
| RθJL | 15 °C/W - Junction-to-lead thermal resistance; allows direct thermal coupling to copper pads for sustained surge dissipation. |
| Polarity | Unidirectional - Cathode-band marked device; used where DC bias polarity is fixed and reverse conduction must be blocked. |
Pinout & Package
DO-214AB (SMC J-Bend) surface-mount package with molded plastic case, matte tin lead-free plating, and cathode band denoting the positive end (anode side opposite band). Mounted on 8.0 mm × 8.0 mm copper pads per terminal per JEDEC standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current sink during clamping | Connected to protected line (e.g., 24 V rail); conducts surge current to ground when VLINE exceeds VBR. |
| Cathode | Reference / Ground return | Marked with color band; tied to system ground or low-impedance return path to complete clamping loop. |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ps - Enables suppression of nanosecond-scale ESD transients before sensitive logic inputs are overstressed. |
| Glass passivated junction | Improved reliability and leakage stability - Reduces parameter drift over temperature and lifetime vs. epoxy-passivated alternatives. |
| MSL Level 1 (260 °C peak) | Compatible with standard lead-free reflow profiles - Eliminates moisture sensitivity concerns during SMT assembly. |
| UL 94V-0 flammability | Self-extinguishing plastic housing - Meets safety requirements for enclosed industrial power supplies and EV charging units. |
| Built-in strain relief | Enhanced mechanical robustness - Resists solder joint fracture under thermal cycling and board flexure in transportation equipment. |
Applications
| Industrial Motor Drives | Automotive Body Control Modules |
|---|---|
Use Scenario: Protection of gate driver ICs and isolated power supplies from IGBT switching-induced voltage spikes and load dump transients. IC Role / Device Role: Primary TVS clamp on 15–24 V auxiliary rails feeding half-bridge drivers and optocouplers. Use Value: Limits clamped voltage to ≤29.2 V, preventing latch-up or permanent damage to 30 V-rated CMOS gate drivers. | Use Scenario: Surge suppression on LIN bus lines and sensor supply rails exposed to battery transients and ISO 7637-2 pulses. IC Role / Device Role: Unidirectional clamping element placed between 12 V rail and ground near microcontroller power pins. Use Value: Withstands 3000 W peak pulses while maintaining <2 µA leakage at 18 V, preserving sleep-mode current budgets. |
| Telecom Power Feeds | Renewable Energy Inverters |
Use Scenario: Input-stage protection on 48 V DC telecom rectifier outputs subject to lightning-induced surges per IEC 61000-4-5. IC Role / Device Role: First-line transient suppressor upstream of DC-DC converters and hot-swap controllers. Use Value: 29.2 V clamping ensures downstream 36 V input-rated converters remain within absolute maximum ratings during 2 kV/1 kA surges. | Use Scenario: DC link surge protection in solar string inverters where PV array wiring introduces long-line induced transients. IC Role / Device Role: Parallel-mounted TVS on 600–1000 V DC bus segments to limit overvoltage during grid fault recovery. Use Value: Though SMDJ18A is rated for lower voltages, it serves in auxiliary 24 V control circuitry - clamping at 29.2 V prevents MCU reset during rapid voltage excursions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SAC18A (Littelfuse) | Same DO-214AB package, identical VRWM (18 V), but higher Vc = 30.0 V at same IPPM; RθJA = 70 °C/W vs. 75 °C/W. | Marginally higher clamping voltage may impact 30 V-rated downstream devices; otherwise drop-in compatible in layout-constrained designs. | Select SAC18A only if tighter VBR tolerance (±5%) is required - SMDJ18A offers ±10% VBR but lower cost and broader distributor availability. |
| 1.5KE18A (ON Semiconductor) | Through-hole DO-201 package; same electrical specs but 3× larger footprint and no MSL1 rating; RθJL = 10 °C/W. | Not suitable for high-density SMT production; requires wave soldering or hand assembly; unsuitable for automated reflow lines. | Choose 1.5KE18A only for legacy through-hole systems or prototyping where thermal margin outweighs board space constraints. |
Compared with SAC18A and 1.5KE18A, the SMDJ18A provides optimal balance of low-profile SMT compatibility, MSL1 reflow readiness, and proven 3000 W surge capability - making it preferred for volume-manufactured industrial and automotive electronics requiring zero layout revision risk.
Availability
SMDJ18A is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, and telecom power feeds requiring stable component supply, consistent parametric performance, and full traceability across production batches.
Supply support for SMDJ18A 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
Alpha & Omega Semiconductor (AOS) is a fabless power semiconductor company specializing in high-efficiency MOSFETs, TVS diodes, and power ICs for computing, consumer, industrial, and automotive markets.
The SMDJ series was developed to deliver high-power, low-clamping TVS protection in compact surface-mount packages - targeting design-in for next-generation power supplies, motor controllers, and EV subsystems where space, thermal performance, and surge immunity are critical.
FAQ
What is the maximum clamping voltage of the SMDJ18A under a 10/1000 µs surge?
The SMDJ18A has a maximum clamping voltage (VC) of 29.2 V when subjected to its rated peak pulse current of 102.8 A on a 10/1000 µs waveform. This value is measured per industry-standard test conditions and defines the upper voltage limit imposed on protected circuitry during surge events - critical for ensuring downstream components like gate drivers or microcontrollers remain within their absolute maximum ratings. The SMDJ18A maintains this clamping performance across its full operating temperature range.
Is the SMDJ18A RoHS and halogen-free compliant?
Yes, the SMDJ18A is an AOS Green Product, meaning it is fully RoHS compliant, lead-free, and halogen-free per AOS' environmental policy. It meets JEDEC J-STD-020 MSL Level 1 moisture sensitivity requirements and carries UL 94V-0 flammability certification. The matte tin lead finish ensures compatibility with standard lead-free reflow processes, and full compliance documentation is available via AOS' website and authorized distribution channels for the SMDJ18A.
How does the SMDJ18A differ from bidirectional variants like SMDJ18CA?
The SMDJ18A is unidirectional, with a single cathode band indicating polarity, and conducts only during reverse-biased overvoltage events - ideal for DC power rails. In contrast, SMDJ18CA is bidirectional, symmetrical in both directions, and used on AC-coupled or floating signal lines like RS-485 or CAN buses. Their breakdown and clamping characteristics apply identically in both directions for SMDJ18CA, whereas SMDJ18A blocks forward current and clamps only in reverse. Both share identical package, thermal specs, and surge ratings.
What is the thermal resistance from junction to ambient for the SMDJ18A?
The SMDJ18A has a typical junction-to-ambient thermal resistance (RθJA) of 75 °C/W when mounted on 8.0 mm × 8.0 mm copper pads per terminal, per JEDEC standards. This value assumes standard PCB layout practices and is essential for calculating steady-state temperature rise under repetitive surge conditions. For improved thermal performance, designers can enhance copper area or add thermal vias - the SMDJ18A's RθJL of 15 °C/W further supports efficient heat transfer to the PCB plane.
Can the SMDJ18A be used in life support applications?
No - the SMDJ18A is explicitly excluded from use in life support devices or systems per AOS' legal disclaimer. As stated in the official datasheet, Alpha & Omega Semiconductor does not authorize applications where failure could reasonably result in significant injury, including surgical implants or systems supporting/sustaining life. Designers must evaluate suitability for their specific end-use, and the SMDJ18A remains appropriate for industrial, automotive, and telecom applications outside this restricted scope.
SMDJ18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Alpha & Omega Semiconductor Inc.
- Package/Case:
- DO-214AB, SMC
- Series:
- -
- 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):
- 102.8A
- Power - Peak Pulse:
- 3000W (3kW)
- 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-214AB
SMDJ18A FAQ
1.How can I place an order for SMDJ18A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMDJ18A 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 SMDJ18A reliable?
The price and inventory of SMDJ18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMDJ18A is usually 5 days.
3.What payment methods are accepted for SMDJ18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMDJ18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMDJ18A?
SMDJ18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMDJ18A 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 SMDJ18A?
For technical support, including SMDJ18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMDJ18A requirements.
6.How does Aetrix verify that SMDJ18A is sourced from the original manufacturer or authorized distributors?
All SMDJ18A 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 SMDJ18A meets industry standards.
7.What is the process for return or replacement of SMDJ18A?
All SMDJ18A units undergo pre-shipment inspection (PSI). If there is an issue with SMDJ18A, 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 SMDJ18A part is unused and in its original packaging.
Return procedure for SMDJ18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMDJ18A Tags
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