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Taiwan Semiconductor Corporation SMDJ18A
- Part No.:
- SMDJ18A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMDJ18A.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:7,994
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Product details
Overview
SMDJ18A from Taiwan Semiconductor is a unidirectional 3000W surface-mount transient voltage suppressor (TVS) diode with a 18V working stand-off voltage (VWM), 20.0–22.1V breakdown voltage (VBR), and 29.2V maximum clamping voltage (VC) at 102.7A peak pulse current. It is designed for primary-level surge protection in DC power rails and signal lines of industrial control systems, automotive ECUs, and telecom interfaces.
For engineers reviewing the SMDJ18A datasheet, SMDJ18A pinout, SMDJ18A application, or SMDJ18A equivalent, key selection criteria include its DO-214AB (SMC) package compatibility, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, sub-1ps response time, 175°C junction rating, and verified clamping performance under 10/1000μs transients.
Technical Context
The SMDJ18A operates as a unidirectional avalanche diode, conducting only in reverse bias above VBR to clamp transient energy into ground. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1µA at 18V), while the DO-214AB package provides low thermal resistance (RθJA = 75°C/W, RθJL = 15°C/W) for reliable power dissipation during repetitive surges.
It meets automotive-grade transient immunity per ISO 7637-2 across all defined pulses (1, 2a, 2b, 3a, 3b), with a peak pulse power rating of 3000W at TA = 25°C and derated linearly above that temperature. The device is rated for 300A non-repetitive forward surge (IFSM) and exhibits a fast response time typically under 1.0ps - critical for protecting sensitive downstream ICs from ESD and lightning-induced spikes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR @ IT=1mA | 20.0–22.1 V - Verified avalanche onset range ensuring predictable turn-on margin |
| VC @ IPPM=102.7A | 29.2 V - Clamped voltage during 10/1000μs surge, limiting stress on protected circuitry |
| PPK | 3000 W - Peak pulse power handling capability per single 1ms transient |
| TJ max | +175 °C - Enables operation in high-ambient environments such as engine bays or industrial enclosures |
| Package | DO-214AB (SMC) - Standardized surface-mount outline with 7.11 × 6.22 mm footprint and matte tin leads |
Pinout & Package
DO-214AB (SMC) package: molded plastic case with cathode band marking; dual-leaded, gull-wing surface-mount configuration; RoHS-compliant, halogen-free, UL 94V-0 rated compound; weight ≈ 0.290g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to system ground or return path in unidirectional TVS configuration |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 12V rail or CAN_H); marked by band on package |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity |
| ISO 7637-2 compliance | Validated immunity to automotive load-dump and inductive-switching transients (Pulse 1/2a/2b/3a/3b) |
| Sub-1ps response time | Clamps transients before propagation to sensitive logic or analog components |
| Moisture sensitivity level 1 | Eliminates need for dry-pack or bake-out prior to reflow soldering |
| Junction-to-lead thermal resistance | 15°C/W - Enables efficient heat transfer to PCB copper, supporting sustained surge duty cycles |
Applications
| Automotive Power Rail Protection | Industrial PLC I/O Protection |
|---|---|
Use Scenario: Protecting 12V/24V supply inputs in body control modules against load dump and alternator transients. IC Role / Device Role / Timing Role: Primary clamping element placed upstream of DC-DC converters and microcontrollers. Use Value: Limits voltage to ≤29.2V during 3000W surges, preventing latch-up or permanent damage to downstream regulators and MCUs. | Use Scenario: Shielding digital input channels of programmable logic controllers from field-wiring induced surges. IC Role / Device Role / Timing Role: Unidirectional TVS on each isolated 24V input channel, referenced to common ground. Use Value: Withstands repeated 10/1000μs transients up to 102.7A without degradation, maintaining signal integrity over 10+ years of industrial operation. |
| Telecom Line Interface Protection | Consumer Power Adapter Input Stage |
Use Scenario: Guarding RS-485 transceiver power pins against ESD and lightning-induced surges in outdoor base stations. IC Role / Device Role / Timing Role: Standoff-clamp TVS on VCC line, coordinated with secondary MOV and series impedance. Use Value: Sub-1ps response ensures clamping initiates before transceiver ICs experience overstress, meeting IEC 61000-4-2 Level 4 (15kV air) requirements. | Use Scenario: Suppressing switching noise and line surges at AC-DC adapter primary-side rectifier output. IC Role / Device Role / Timing Role: Secondary-side TVS on bulk capacitor rail, absorbing residual transients escaping primary-stage filtering. Use Value: 175°C TJ rating allows placement near hot transformers without derating, improving adapter MTBF and safety certification margin. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SAC18 | Lower PPK (1500W), higher VC (32.4V at 72A), same DO-214AB package | Not suitable for ISO 7637-2 Pulse 1 (load dump); limited to lower-energy ESD/inductive spikes | Select when cost sensitivity outweighs automotive surge margin and peak power demand is <1500W |
| 1.5SMC18A | Same VWM/VBR/VC specs, identical DO-214AB package, but rated for 1500W PPK (not 3000W) | Lacks validation for ISO 7637-2 Pulse 2b and 3b; not qualified for automotive under-hood use | Acceptable for industrial or consumer applications where full 3000W surge headroom is not required |
Compared with SAC18 and 1.5SMC18A, the SMDJ18A delivers 100% higher peak power handling (3000W vs. 1500W) and certified ISO 7637-2 compliance - making it the only choice for automotive power rail protection requiring robust load-dump immunity and long-term reliability under thermal stress.
Availability
SMDJ18A is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, and telecom infrastructure requiring stable component supply, extended lifecycle support, and traceable sourcing for production programs.
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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated Taiwanese semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for industrial and automotive markets.
The SMDJ series was developed specifically for high-energy transient suppression in harsh environments, targeting ISO 7637-2 compliance and extended temperature operation up to +175°C.
FAQ
What is the maximum clamping voltage of the SMDJ18A under standard test conditions?
The SMDJ18A has a maximum clamping voltage (VC) of 29.2 V when subjected to a 10/1000 μs waveform with a peak pulse current (IPPM) of 102.7 A. This value is measured at TA = 25°C and defines the upper voltage limit imposed on protected circuitry during surge events. The SMDJ18A maintains this clamping performance consistently across its operational temperature range, making it suitable for designs where downstream ICs have strict absolute maximum voltage ratings.
Is the SMDJ18A suitable for bidirectional transient protection?
No, the SMDJ18A is a unidirectional TVS diode intended for DC line protection with defined polarity. For bidirectional applications, the SMDJ18CA variant must be used - it features symmetrical breakdown in both directions and is marked with "DET" on the package. Using the SMDJ18A in a bidirectional configuration risks failure during positive-going transients due to lack of forward conduction capability beyond its VF rating.
What is the thermal resistance from junction to ambient for the SMDJ18A in standard mounting conditions?
The SMDJ18A has a typical junction-to-ambient thermal resistance (RθJA) of 75°C/W when mounted on a standard JEDEC 2S2P test board (1 inch² copper pad). This value assumes no additional thermal vias or heatsinking. For high-reliability applications, designers should verify board layout thermal performance using the device's RθJL of 15°C/W and ensure adequate copper area to maintain TJ ≤ 175°C under worst-case surge repetition rates.
Does the SMDJ18A meet automotive qualification standards beyond ISO 7637-2?
The SMDJ18A is explicitly tested and compliant with ISO 7637-2 (Pulse 1, 2a, 2b, 3a, 3b) for automotive transient immunity, but it is not AEC-Q200 qualified as a standalone component. Its construction - including glass-passivated junction, MSL1 rating, and 175°C TJ rating - supports automotive use when validated within the full system-level EMC test plan. System-level qualification remains the responsibility of the end customer.
What is the marking code printed on the SMDJ18A package?
The SMDJ18A is marked with "PET" on the top surface of its DO-214AB (SMC) package. This 3-character code uniquely identifies the 18V unidirectional variant within the SMDJ family and distinguishes it from the bidirectional SMDJ18CA (marked "DET") and other voltage grades. The cathode band is present on the same end as the marking, indicating the cathode terminal.
SMDJ18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AB, SMC
- Series:
- SMDJ
- 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):
- 102.7A
- Power - Peak Pulse:
- 3000W (3kW)
- Power Line Protection:
- No
- Applications:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMC)
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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