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Taiwan Semiconductor Corporation SMAJ18CH
- Part No.:
- SMAJ18CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CH.pdf
- Description:
- TVS DIODE 18VWM 32.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,827
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Product details
Overview
SMAJ18CH from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 18V working stand-off voltage (VWM), 20.0–24.4V breakdown voltage (VBR), and 32.2V maximum clamping voltage (VC) at 12.4A peak pulse current. It delivers AEC-Q101 qualification and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive power line protection.
For engineers reviewing the SMAJ18CH datasheet, SMAJ18CH pinout, SMAJ18CH application, or SMAJ18CH equivalent, this device is selected for robust overvoltage protection in DC/DC converters, SMPS inputs, lighting drivers, and automotive electronics where fast response (<1.0ps), low leakage (<1µA @ VWM), and stable clamping under 10/1000µs transients are critical.
Technical Context
The SMAJ18CH operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its 20.0–24.4V breakdown range at 1mA test current. Its glass-passivated junction ensures stable VBR tolerance and long-term reliability under repetitive surge stress.
Designed for automotive-grade environments, it supports –55°C to +150°C junction operation, complies with JESD201 Class 2 whisker resistance, and achieves moisture sensitivity level 1 per J-STD-020 - enabling lead-free reflow without popcorn risk or delamination.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before conduction begins; defines safe DC blocking threshold. |
| VBR min/max | 20.0 / 24.4 V @ 1 mA - Confirmed breakdown range ensures predictable turn-on during transients without premature clamping. |
| VC @ IPPM | 32.2 V @ 12.4 A - Clamping voltage under 10/1000µs surge limits downstream IC stress to safe levels. |
| PPPM | 400 W - Peak pulse power rating enables handling of high-energy load dump or inductive switching events. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves efficiency in high-impedance bias networks and battery-powered systems. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline compatible with automated placement and IPC-7351B land patterns. |
Pinout & Package
DO-214AC (SMA) package: cathode-banded unidirectional configuration with two terminals - anode (unmarked end) and cathode (banded end). Matte tin-plated leads meet J-STD-002 solderability requirements; polarity is marked via molded cathode band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Reverse voltage reference node | Connected to system ground or low-side return path; establishes reference for clamping action. |
| Cathode | Transient energy sink / Clamping output node | Connected to protected line (e.g., 12V rail); conducts surge current to ground when VREV > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive underhood and powertrain applications per stress test requirements including HTOL, TCT, and ESD. |
| Fast response time <1.0 ps | Enables suppression of nanosecond-scale ESD and lightning-induced transients before sensitive circuitry is damaged. |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Guarantees survivability against real-world automotive electrical disturbances including load dump and alternator ripple. |
| RoHS & halogen-free | Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for environmentally compliant manufacturing and end-of-life processing. |
Applications
| Automotive Power Line Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting 12V battery-fed ECUs from load dump transients up to ±125V per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp surges before they reach regulator ICs. Use Value: Limits clamped voltage to ≤32.2V, preventing damage to 36V-rated buck controllers and maintaining system uptime. | Use Scenario: Safeguarding isolated flyback converter primary-side input against switching spikes and external surges. IC Role / Device Role / Timing Role: Standoff protector on main DC bus; activated only during overvoltage events exceeding 18V, remaining invisible during normal operation. Use Value: Enables use of lower-voltage-rated MOSFETs and capacitors while meeting IEC 61000-4-5 Level 3 immunity requirements. |
| LED Driver Power Supply | USB-C PD Adapter Output Stage |
Use Scenario: Suppressing inductive kickback from LED string current regulation circuits during hot-plug or dimming transitions. IC Role / Device Role / Timing Role: Parallel-connected TVS across output terminals to absorb stored inductor energy and prevent voltage overshoot. Use Value: Maintains LED driver output stability by limiting transient excursions to <32.2V, avoiding false OVP shutdowns. | Use Scenario: Secondary-side overvoltage protection in 20V USB-C PD adapters subject to transient coupling from primary-side switching noise. IC Role / Device Role / Timing Role: Final-stage clamp on regulated 20V output rail, acting as last-line defense before connected devices. Use Value: Ensures compliance with USB-IF VBUS overvoltage limits (≤21.5V) during fault conditions without sacrificing steady-state efficiency. |
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 VBR range (20.0–22.1V) and higher IR (1µA vs. <1µA typical); same DO-214AC package and 400W rating. | Slightly tighter VBR tolerance suits precision clamping needs but offers marginally reduced surge margin at high temperature. | Select SMAJ18A when tighter breakdown consistency is prioritized over absolute minimum leakage. |
| SMBJ18C | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; 600W PPPM rating (vs. 400W). | Higher power handling supports longer-duration transients; requires larger PCB footprint and different pad layout. | Choose SMBJ18C when system-level surge testing exceeds 400W or thermal derating demands extra margin. |
Compared with SMAJ18CH, SMAJ18A provides tighter VBR control at minor leakage cost, while SMBJ18C trades package size for 50% higher pulse power - making SMAJ18CH the optimal balance of compactness, automotive qualification, and standardized 400W surge capability.
Availability
SMAJ18CH is available at Aetrix Electronics and suitable for automotive electronics, industrial DC/DC converters, and LED lighting systems requiring stable component supply, AEC-Q101 compliance, and ISO 7637-2 immunity assurance.
Supply support for SMAJ18CH 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, MOSFETs, and power management components.
The SMAJ series was developed specifically for automotive and industrial transient suppression, emphasizing AEC-Q101 reliability, tight parametric control, and compatibility with high-speed automated assembly lines.
FAQ
What is the clamping voltage of SMAJ18CH under standard 10/1000µs surge conditions?
The SMAJ18CH has a maximum clamping voltage (VC) of 32.2 V at 12.4 A peak pulse current under the 10/1000µs waveform. This value is measured per JEDEC standards and guarantees that protected circuitry sees no more than 32.2 V during defined transient events - critical for safeguarding 36V-rated regulators and interface ICs in automotive applications.
Is SMAJ18CH unidirectional or bidirectional, and how is polarity identified?
SMAJ18CH is a unidirectional TVS diode. Polarity is indicated by a molded cathode band on the DO-214AC (SMA) package body; the banded end is the cathode and must be connected toward the protected line, while the anode connects to ground or the return path. Bidirectional variants use "CAH" suffix (e.g., SMAJ18CAH).
Does SMAJ18CH meet automotive qualification standards?
Yes, SMAJ18CH is AEC-Q101 qualified and certified to withstand automotive-grade stress tests including high-temperature operating life, temperature cycling, and ESD. It also meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b requirements - confirming suitability for 12V and 24V vehicle electrical systems.
What is the maximum junction temperature and storage range for SMAJ18CH?
The SMAJ18CH supports an operating junction temperature range of –55°C to +150°C and a storage temperature range of –55°C to +150°C. These ratings enable deployment in under-hood automotive modules, industrial motor drives, and outdoor lighting enclosures where ambient temperatures exceed 105°C.
How does SMAJ18CH compare to SMAJ18AH in terms of breakdown voltage and leakage?
SMAJ18CH specifies a VBR range of 20.0–24.4 V and typical IR <1 µA at 18 V, whereas SMAJ18AH has a tighter VBR of 20.0–22.1 V but identical IR limit. The "H" variant offers broader surge margin at elevated temperature, while the "AH" variant prioritizes tighter VBR consistency for precision clamping applications.
SMAJ18CH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- 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:
- 32.2V
- Current - Peak Pulse (10/1000µs):
- 12.4A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ18CH FAQ
1.How can I place an order for SMAJ18CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CH 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 SMAJ18CH reliable?
The price and inventory of SMAJ18CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18CH is usually 5 days.
3.What payment methods are accepted for SMAJ18CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CH?
SMAJ18CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CH 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 SMAJ18CH?
For technical support, including SMAJ18CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CH requirements.
6.How does Aetrix verify that SMAJ18CH is sourced from the original manufacturer or authorized distributors?
All SMAJ18CH 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 SMAJ18CH meets industry standards.
7.What is the process for return or replacement of SMAJ18CH?
All SMAJ18CH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CH, 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 SMAJ18CH part is unused and in its original packaging.
Return procedure for SMAJ18CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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