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Alpha & Omega Semiconductor Inc. SMDJ18CA
- Part No.:
- SMDJ18CA
- Manufacturer:
- Alpha & Omega Semiconductor Inc.
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMDJ18CA.pdf
- Description:
- 1CH 18V BIDIRECTIONAL 3000W SMD
- Quantity:
- Payment:
- Shipping:
Inventory:9,826
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Product details
Overview
SMDJ18CA from Alpha & Omega Semiconductor is a bi-directional transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, designed for robust overvoltage protection in DC power rails and signal lines. It features 18.0 V reverse stand-off voltage (VRWM), 20.0–22.1 V breakdown voltage (VBR @ 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.
For engineers reviewing the SMDJ18CA datasheet, pinout, applications, or equivalent options, key selection criteria include bidirectional clamping capability, low clamping ratio (Vc/VBR ≈ 1.42), JEDEC-compliant DO-214AB surface-mount package, and suitability for IEC 61000-4-2/4-5 compliant surge protection in industrial power supplies and automotive ECUs.
Technical Context
The SMDJ18CA operates as a bi-directional avalanche diode, providing symmetrical clamping in both polarities without requiring external polarity management. Its glass-passivated junction ensures stable VBR tolerance (±5% typical) and low temperature coefficient (0.1% × VBR/°C), enabling predictable performance across –55°C to +150°C junction temperature range.
It delivers sub-1 ps response time from 0 V to breakdown, with thermal resistance of 15°C/W (junction-to-lead) when mounted on 8.0 mm × 8.0 mm copper pads. The device meets MSL Level 1 per J-STD-020 and UL 94V-0 flammability standard, supporting lead-free reflow up to 260°C peak.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18.0 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 20.0 V / 22.1 V @ 1 mA - Confirmed avalanche onset range under standardized test current |
| Vc @ IPPM | 29.2 V @ 102.8 A - Clamped voltage during 10/1000 µs surge, defining protected circuit stress level |
| PPPM | 3000 W - Peak surge energy handling capacity on standard lightning/surge waveform |
| TJ max | +150 °C - Maximum allowable junction temperature for reliable long-term operation |
| Polarity | Bi-directional - Enables single-device protection of AC-coupled or floating signal paths |
| Package | DO-214AB (SMC J-Bend) - Industry-standard surface-mount outline with strain relief and solderable matte tin leads |
Pinout & Package
DO-214AB (SMC) package: molded plastic case with J-bend terminals; cathode band denotes polarity for unidirectional variants, but SMDJ18CA is bi-directional and has no functional polarity marking-both terminals are electrically symmetric.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode/Cathode (symmetrical) | Transient conduction path | Both terminals serve identical clamping function; no directional bias required in PCB layout |
| Case (plastic body) | Thermal and mechanical interface | Provides strain relief and thermal path to PCB copper; no electrical connection |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ps - Ensures clamping activation before sensitive downstream ICs experience overvoltage stress |
| Glass-passivated junction | Stable VBR drift <0.1%/°C - Maintains consistent clamping threshold across temperature extremes |
| MSL Level 1 rating | Compatible with standard Pb-free reflow (260°C peak) - Eliminates moisture sensitivity concerns during assembly |
| UL 94V-0 flammability | Self-extinguishing plastic housing - Meets safety requirements for enclosed industrial and automotive enclosures |
| Strain relief construction | Reduces mechanical stress on solder joints during thermal cycling - Enhances field reliability in high-vibration environments |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Protecting 24 V DC input rails in programmable logic controllers (PLCs) against load dump and inductive switching transients. IC Role / Device Role: Primary surge suppression element placed at board-level input connector. Use Value: Limits transient voltage to ≤29.2 V during 102.8 A surges, preventing damage to upstream DC-DC converters and microcontrollers. | Use Scenario: Safeguarding LIN bus and sensor supply lines in BCMs exposed to ISO 7637-2 Pulse 1/2a/5a events. IC Role / Device Role: Bi-directional TVS placed across power rail and ground near connector entry point. Use Value: Symmetrical clamping enables single-device protection of bidirectional communication lines without polarity constraints. |
| Telecom Remote Radio Unit (RRU) | Renewable Energy Inverter DC Link |
Use Scenario: Shielding Ethernet PHY power pins and RS-485 transceivers from ESD and lightning-induced surges in outdoor base stations. IC Role / Device Role: Secondary-level protection after gas discharge tube (GDT) front-end. Use Value: Low clamping voltage (29.2 V) prevents overstress on 3.3 V/5 V logic interfaces while surviving 3 kW pulses. | Use Scenario: Protecting gate drivers and sensing circuits on 400–800 V DC link in solar inverters subjected to grid-switching transients. IC Role / Device Role: Localized clamping on auxiliary 15–24 V bias rails feeding isolated gate drivers. Use Value: 150°C max junction temperature rating supports operation in thermally constrained inverter enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SAC18CA (Littelfuse) | Same VRWM (18 V), slightly higher Vc (30.0 V @ 100 A), DO-214AB package | Identical mounting and footprint; marginally higher clamping voltage reduces protected circuit headroom | Select when Littelfuse supply chain alignment or legacy BOM compatibility is prioritized |
| SMBJ18CA (ON Semiconductor) | Lower PPPM (600 W), same VRWM/VBR, SMB package (smaller footprint, lower thermal mass) | Not suitable for 3 kW surge events; limited to lower-energy transients per IEC 61000-4-5 Class 3 | Choose only for space-constrained designs where surge threat level is confirmed ≤600 W |
Compared with SAC18CA and SMBJ18CA, the SMDJ18CA uniquely delivers 3000 W surge capability in DO-214AB, making it the only option among the three qualified for high-energy automotive load dump and industrial 4 kV/2 kA surge testing per IEC 61000-4-5.
Availability
SMDJ18CA is available at Aetrix Electronics and suitable for industrial power supplies, automotive electronic control units, and telecom infrastructure requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SMDJ18CA 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 modules for industrial, computing, and automotive markets.
The SMDJxxxA/CA series was engineered specifically for high-power transient suppression in harsh-environment applications, emphasizing rugged packaging, repeatable clamping, and compliance with AEC-Q101 and IEC 61000-4-5 standards.
FAQ
What is the clamping voltage of SMDJ18CA at its rated peak pulse current?
The SMDJ18CA exhibits a maximum clamping voltage (Vc) of 29.2 V when subjected to its rated peak pulse current (IPPM) of 102.8 A on a 10/1000 µs waveform. This value defines the upper voltage limit imposed on protected circuitry during surge events and is measured under standardized test conditions per JEDEC standards. The SMDJ18CA maintains this clamping performance consistently due to its glass-passivated junction and low dynamic impedance.
Is SMDJ18CA suitable for protecting bidirectional communication lines like RS-485?
Yes, the SMDJ18CA is explicitly designed for bidirectional use, as indicated by the "CA" suffix and confirmed in its electrical characteristics table. Its symmetrical breakdown behavior in both directions allows placement across differential pairs or AC-coupled signal lines without polarity concerns. The SMDJ18CA's 29.2 V clamping voltage provides adequate margin for 3.3 V or 5 V RS-485 transceivers when used with appropriate series impedance.
What is the thermal resistance of SMDJ18CA, and how does it affect PCB layout?
The SMDJ18CA has a typical junction-to-lead thermal resistance (RθJL) of 15°C/W when mounted on 8.0 mm × 8.0 mm copper pads per terminal. This value assumes optimal thermal land pattern per JEDEC DO-214AB recommendations. To maintain safe junction temperatures under repeated surges, PCB layout must provide sufficient copper area and thermal vias-reducing pad size below specification increases RθJA and risks thermal runaway during high-duty-cycle events. The SMDJ18CA's thermal design directly impacts its sustained surge endurance.
Does SMDJ18CA meet automotive qualification standards?
The SMDJ18CA is not AEC-Q101 qualified as a standalone part per the provided datasheet, though its construction (glass-passivated junction, MSL Level 1, 150°C TJ max) aligns with key automotive reliability requirements. Engineers deploying SMDJ18CA in automotive applications must perform system-level validation per ISO 7637-2 and ISO 16750-2. For AEC-Q101-certified alternatives, consider AOS' AQxxxCA series-SMDJ18CA serves best in non-safety-critical automotive subsystems where full qualification is not mandated.
How does the SMDJ18CA compare to SMDJ18A in terms of circuit protection capability?
The SMDJ18CA is bi-directional, while SMDJ18A is unidirectional-this is the fundamental distinction affecting circuit integration. Both share identical VRWM (18.0 V), VBR (20.0–22.1 V), and Vc (29.2 V), but SMDJ18CA protects AC or floating nodes without polarity constraints, whereas SMDJ18A requires correct cathode orientation relative to system ground. The SMDJ18CA eliminates risk of reverse installation in bidirectional signal paths, making it preferred for LIN, CAN FD, and Ethernet PHY protection where polarity cannot be guaranteed.
SMDJ18CA 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:
- -
- Bidirectional Channels:
- 1
- 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
SMDJ18CA FAQ
1.How can I place an order for SMDJ18CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMDJ18CA 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 SMDJ18CA reliable?
The price and inventory of SMDJ18CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMDJ18CA is usually 5 days.
3.What payment methods are accepted for SMDJ18CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMDJ18CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMDJ18CA?
SMDJ18CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMDJ18CA 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 SMDJ18CA?
For technical support, including SMDJ18CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMDJ18CA requirements.
6.How does Aetrix verify that SMDJ18CA is sourced from the original manufacturer or authorized distributors?
All SMDJ18CA 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 SMDJ18CA meets industry standards.
7.What is the process for return or replacement of SMDJ18CA?
All SMDJ18CA units undergo pre-shipment inspection (PSI). If there is an issue with SMDJ18CA, 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 SMDJ18CA part is unused and in its original packaging.
Return procedure for SMDJ18CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMDJ18CA Tags
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