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Taiwan Semiconductor Corporation SMDJ18AH
- Part No.:
- SMDJ18AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMDJ18AH.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:5,618
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Product details
Overview
SMDJ18AH from Taiwan Semiconductor is a unidirectional 3000W surface-mount transient voltage suppressor (TVS) diode with a working stand-off voltage of 18 V, breakdown voltage range of 20.0–22.1 V, and clamping voltage of 29.2 V at 102.7 A peak pulse current. It features DO-214AB (SMC) packaging, AEC-Q101 qualification, and is designed for automotive and industrial ESD/transient protection in power rails and I/O lines.
For engineers reviewing the SMDJ18AH datasheet, SMDJ18AH pinout, SMDJ18AH application, or SMDJ18AH equivalent, key selection criteria include its 18 V stand-off rating, 3000 W peak pulse power capability, ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b), fast sub-1 ps response time, and unidirectional polarity marking - all critical for robust overvoltage immunity in 12 V automotive systems and industrial control interfaces.
Technical Context
The SMDJ18AH operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its 20.0–22.1 V breakdown threshold. Its glass-passivated junction ensures stable clamping performance under repetitive transients, while the DO-214AB package supports automated placement and meets JESD201 Class 2 whisker resistance.
It delivers 29.2 V clamping at 102.7 A (10/1000 µs waveform), with thermal resistance of 75 °C/W (junction-to-ambient) and 15 °C/W (junction-to-lead). The device sustains 300 A non-repetitive forward surge (8.3 ms half-sine) and exhibits ≤5 µA reverse leakage at 18 V, enabling reliable hold-off in 12 V nominal systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage; defines safe DC/AC rail voltage before conduction begins. |
| VBR @ IT=1 mA | 20.0–22.1 V - Breakdown voltage range; guarantees reliable avalanche initiation across process variation and temperature. |
| VC @ IPPM=102.7 A | 29.2 V - Clamping voltage under 3000 W transient; limits downstream IC stress during ISO 7637-2 Pulse 1/2/3 events. |
| PPK | 3000 W - Peak pulse power rating (1 ms); enables suppression of high-energy load-dump and lightning-induced surges. |
| IFSM | 300 A - Peak forward surge current (8.3 ms); supports robust handling of inductive kickback in relay or solenoid drive circuits. |
| TJ Range | −55 to +175 °C - Extended junction temperature range; validated for under-hood automotive and industrial environments. |
| RθJA | 75 °C/W - Junction-to-ambient thermal resistance; informs PCB copper area requirements for sustained power dissipation. |
Pinout & Package
Package: DO-214AB (SMC), surface-mount, unidirectional configuration with cathode band marking. Matte tin-plated leads, UL 94V-0 molding compound, 0.290 g typical weight.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Reverse voltage reference | Connected to protected line (e.g., 12 V rail); conducts during forward surge or clamps reverse transients. |
| Cathode | Clamping node / Ground reference | Connected to system ground or low-impedance return path; defines polarity and establishes clamping voltage reference. |
| Cathode band | Physical polarity indicator | Visible marking on package body; ensures correct orientation during automated placement and manual inspection. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronics per stress test requirements (HTOL, TC, HAST, etc.), supporting Tier-1 supply chain acceptance. |
| ISO 7637-2 compliance | Meets Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (line impedance coupling) waveforms without failure. |
| Glass passivated junction | Enhances long-term reliability and stability of breakdown voltage under thermal cycling and humidity exposure. |
| Fast response time <1.0 ps | Enables effective suppression of nanosecond-scale ESD events (IEC 61000-4-2) before sensitive ICs experience latch-up or damage. |
| Moisture sensitivity level 1 | Eliminates need for dry-pack or bake-out prior to reflow; compatible with standard SMT assembly processes. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs, lighting modules, and body control units against load dump and alternator transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp voltage spikes above 29.2 V. Use Value: Prevents damage to microcontrollers and CAN transceivers by limiting peak rail voltage to ≤29.2 V during 3000 W ISO 7637-2 Pulse 5a events. | Use Scenario: Shielding 4–20 mA analog sensor inputs and RS-485 communication lines from ESD and field-induced surges. IC Role / Device Role / Timing Role: Standoff protection element mounted at connector entry point, shunting transients to local ground before signal conditioning circuitry. Use Value: Maintains signal integrity by suppressing >8 kV contact ESD (IEC 61000-4-2) with <1 ps response, avoiding false triggering or ADC saturation. |
| Telecom Power Supply Input | Consumer Equipment USB/DC Jack Protection |
Use Scenario: Safeguarding AC/DC adapter outputs and PoE-powered equipment front-ends from lightning-induced surges on primary-side DC bus. IC Role / Device Role / Timing Role: Primary-side TVS on 24–48 V input rail, coordinated with upstream fuses and common-mode chokes. Use Value: Absorbs up to 3000 W transient energy (10/1000 µs) without degradation, preserving downstream DC-DC converter reliability. | Use Scenario: Protecting USB-C PD ports and barrel-jack inputs in portable audio, medical monitors, and smart home hubs from user-handling ESD and miswiring. IC Role / Device Role / Timing Role: Unidirectional clamping device between VBUS and GND, sized for 18 V nominal input with margin for ripple and tolerance. Use Value: Limits clamped voltage to 29.2 V during 15 kV air discharge, preventing gate oxide rupture in USB power switches and PMICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Lower peak power (400 W vs. 3000 W); same DO-214AC (SMA) package; VC = 29.2 V at 13.7 A. | Not suitable for ISO 7637-2 Pulse 5a or high-energy load dump; limited to low-power I/O or signal-line protection. | Select SMDJ18AH when 3000 W surge immunity is required; SMAJ18A only for cost-sensitive, low-energy applications. |
| SMCJ18A | Same 3000 W rating and DO-214AB (SMC) package; identical VWM, VBR, VC, and thermal specs; differs only in manufacturer (Bourns vs. Taiwan Semiconductor). | No functional or layout difference; fully interchangeable in existing designs requiring AEC-Q101-compliant 18 V TVS. | SMCJ18A offers second-source availability but requires validation of lot traceability and qualification documentation for automotive use. |
Compared with SMAJ18A and SMCJ18A, the SMDJ18AH provides identical clamping performance to SMCJ18A at full 3000 W rating while offering superior surge capacity versus SMAJ18A - making it the preferred choice for automotive power rail and industrial mains-connected protection where energy absorption is critical.
Availability
SMDJ18AH is available at Aetrix Electronics and suitable for automotive electronics, industrial control systems, and telecom power supply designs requiring stable component supply, AEC-Q101 qualification, and high-energy transient immunity.
Supply support for SMDJ18AH 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 Company (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs, with global distribution and AEC-Q101-certified production lines.
The SMDJ series is engineered specifically for high-reliability automotive and industrial transient suppression, emphasizing robustness under ISO 7637-2 pulses, extended temperature operation, and automated assembly compatibility.
FAQ
What is the maximum clamping voltage of the SMDJ18AH under rated surge conditions?
The SMDJ18AH has a maximum clamping voltage (VC) of 29.2 V when subjected to its peak pulse current (IPPM) of 102.7 A using the 10/1000 µs waveform. This value is measured at TA = 25°C and ensures downstream components see no more than 29.2 V during standardized surge events such as ISO 7637-2 Pulse 1 or 2b. The SMDJ18AH maintains this clamping performance across its qualified temperature range.
Is the SMDJ18AH suitable for bidirectional transient protection?
No, the SMDJ18AH is a unidirectional TVS diode intended for DC rail protection with defined anode-cathode polarity. For bidirectional applications, the SMDJ18CAH variant must be used - it shares the same package and clamping characteristics but supports symmetrical voltage transients in both directions. Using SMDJ18AH in a bidirectional configuration risks improper clamping and potential device failure.
Does the SMDJ18AH meet automotive qualification standards?
Yes, the SMDJ18AH is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 requirements for Pulse 1, 2a, 2b, 3a, and 3b. Its construction - including glass-passivated junction, DO-214AB package, and moisture sensitivity level 1 - aligns with automotive manufacturing and reliability expectations. The SMDJ18AH is documented in Taiwan Semiconductor's AEC-Q101 certificate scope for transient voltage suppressors.
What is the thermal resistance and how does it affect PCB layout for the SMDJ18AH?
The SMDJ18AH has a junction-to-ambient thermal resistance (RθJA) of 75 °C/W and junction-to-lead resistance (RθJL) of 15 °C/W. To maintain safe operation during repetitive surges or elevated ambient temperatures, the PCB must provide adequate copper area - typically ≥100 mm² per pad with internal thermal vias - to dissipate heat. Layout directly impacts steady-state power handling (PD = 6.5 W at 25°C), especially in enclosed enclosures.
How does the SMDJ18AH compare to the SMDJ18CAH in terms of electrical behavior?
The SMDJ18AH and SMDJ18CAH share identical VWM (18 V), VBR (20.0–22.1 V), VC (29.2 V), and PPK (3000 W) ratings, but differ in polarity: SMDJ18AH is unidirectional (anode-to-cathode conduction), while SMDJ18CAH is bidirectional (symmetrical clamping). Their marking codes (PET vs. DET) and cathode band presence also differ. Both are DO-214AB packaged and AEC-Q101 qualified, but SMDJ18CAH is required for AC-coupled or floating signal line protection.
SMDJ18AH 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 ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMC)
SMDJ18AH FAQ
1.How can I place an order for SMDJ18AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMDJ18AH 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 SMDJ18AH reliable?
The price and inventory of SMDJ18AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMDJ18AH is usually 5 days.
3.What payment methods are accepted for SMDJ18AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMDJ18AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMDJ18AH?
SMDJ18AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMDJ18AH 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 SMDJ18AH?
For technical support, including SMDJ18AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMDJ18AH requirements.
6.How does Aetrix verify that SMDJ18AH is sourced from the original manufacturer or authorized distributors?
All SMDJ18AH 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 SMDJ18AH meets industry standards.
7.What is the process for return or replacement of SMDJ18AH?
All SMDJ18AH units undergo pre-shipment inspection (PSI). If there is an issue with SMDJ18AH, 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 SMDJ18AH part is unused and in its original packaging.
Return procedure for SMDJ18AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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