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Taiwan Semiconductor Corporation SMF18A
- Part No.:
- SMF18A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF18A.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:7,620
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Product details
Overview
SMF18A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in SOD-123W package, rated for 200 W peak pulse power (10/1000 µs), 18 V working stand-off voltage (VWM), and 29.2 V maximum clamping voltage (VC) at 6.8 A peak impulse current - designed to protect automotive and industrial control ICs against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMF18A datasheet, SMF18A pinout, SMF18A application, or SMF18A equivalent, key selection criteria include clamping performance under 10/1000 µs surge, low leakage (<1 µA @ 18 V), compliance with ISO 7637-2, moisture sensitivity level 1, and RoHS/halogen-free qualification - all verified for SOD-123W assembly in automated PCB production.
Technical Context
The SMF18A operates as a unidirectional avalanche diode with glass-passivated junction, delivering precise breakdown voltage (VBR = 20.0–22.1 V @ IT = 1 mA) and stable clamping behavior up to TJ = 175 °C. Its thermal resistance profile (RθJL = 33 °C/W, RθJA = 100 °C/W) is characterized on a 5 mm × 5 mm copper pad PCB per JESD51-2.
It meets ISO 7637-2 immunity requirements for automotive electronics, including Pulse 1 (inductive load dump suppression), Pulse 2a (battery disconnect transient), and Pulse 3a/3b (capacitive coupling noise). The device exhibits <1 µA reverse leakage at VWM and maintains clamping integrity across -55 °C to +175 °C operating range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before clamping initiates |
| VBR min/max | 20.0 / 22.1 V @ 1 mA - Confirmed avalanche breakdown range ensures reliable turn-on margin above VWM |
| VC @ IPPM | 29.2 V @ 6.8 A - Clamping voltage during 10/1000 µs surge defines protected circuit's max transient exposure |
| PPPM | 200 W - Peak pulse power rating determines survivability against standardized automotive transients |
| IR @ VWM | <1 µA - Ultra-low leakage preserves signal integrity and battery life in always-on systems |
| Package | SOD-123W - Surface-mount outline with matte tin leads, UL 94V-0 molding, and J-STD-020 Level 1 moisture sensitivity |
Pinout & Package
SOD-123W package: single-diode unidirectional configuration with cathode band marking polarity; 0.016 g weight; 5 mm × 5 mm Cu pad thermal test board reference; lead finish compliant with J-STD-002 solderability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction path | Connected to system ground or low-side return in unidirectional TVS configuration |
| Cathode | Clamping node | Connected to protected line (e.g., CAN_H, LIN, sensor supply); cathode band identifies this terminal |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR over temperature and long-term reliability in harsh environments |
| ISO 7637-2 compliance | Validated protection against automotive load-dump and switching transients without external circuitry |
| Moisture sensitivity Level 1 | Enables standard SMT reflow without baking or special handling prior to assembly |
| RoHS & halogen-free | Meets IEC 61249-2-21 and global environmental compliance mandates for automotive and industrial use |
Applications
| Automotive CAN Bus Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting CAN_H/CAN_L lines in 12 V vehicle networks from load-dump and ESD events. IC Role / Device Role / Timing Role: Unidirectional TVS placed between CAN transceiver pins and chassis ground to clamp transients below IC damage threshold. Use Value: Clamps to 29.2 V at 6.8 A, keeping transceiver input within safe operating area during ISO 7637-2 Pulse 2a/3b events. | Use Scenario: Safeguarding analog output (4–20 mA) or digital I/O (RS-485) of PLC modules from inductive kickback. IC Role / Device Role / Timing Role: Standoff protection element on field-side signal lines, absorbing energy from relay coil deactivation. Use Value: 200 W peak power rating handles repetitive 10/1000 µs surges common in factory automation without degradation. |
| LED Driver Supply Line Protection | Automotive Body Control Module (BCM) |
Use Scenario: Shielding constant-current LED driver ICs from battery rail transients during ignition or alternator regulation faults. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 18 V input rail, placed upstream of DC-DC converter input. Use Value: 18 V VWM aligns with nominal 12 V system derating; 29.2 V VC prevents downstream regulator latch-up. | Use Scenario: Securing microcontroller I/O and power rails in BCM units exposed to vehicle-level EFT and surge noise. IC Role / Device Role / Timing Role: Point-of-load TVS on MCU VDD, reset, or wake-up lines to maintain functional safety integrity. Use Value: Low IR (<1 µA) avoids loading low-power sleep states; SOD-123W footprint supports high-density layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18A | Higher PPPM (600 W), larger SMB package (vs. SOD-123W), higher VC (30.0 V @ 19.9 A) | Better suited for higher-energy transients; requires larger PCB area and different thermal design | Select when surge energy exceeds 200 W or when existing SMB footprint is fixed |
| P6SMB18A | Same SMB package as SMBJ18A; identical electrical specs but different branding and qualification history | Used in legacy industrial designs; may lack latest AEC-Q200 stress screening | Prefer SMF18A for new automotive designs requiring J-STD-020 Level 1 and ISO 7637-2 validation |
Compared with SMBJ18A and P6SMB18A, the SMF18A offers optimized space efficiency (SOD-123W), guaranteed Level 1 moisture sensitivity, and direct ISO 7637-2 compliance - making it ideal for compact, high-reliability automotive and industrial PCBs where thermal and layout constraints limit larger packages.
Availability
SMF18A is available at Aetrix Electronics and suitable for automotive CAN bus protection, industrial sensor interface hardening, and LED driver supply line safeguarding requiring stable component supply and full traceability.
Supply support for SMF18A 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for automotive, industrial, and consumer markets.
The SMF18A belongs to TSC's SMF series of surface-mount TVS diodes engineered specifically for ISO 7637-2-compliant transient suppression in space-constrained automotive ECUs and industrial controllers.
FAQ
What is the breakdown voltage range of the SMF18A?
The SMF18A has a minimum breakdown voltage (VBR) of 20.0 V and a maximum of 22.1 V, measured at 1 mA test current per the official Taiwan Semiconductor datasheet. This tight VBR window ensures consistent clamping onset above its 18 V working stand-off voltage and provides predictable protection behavior in automotive and industrial circuits where SMF18A is deployed.
Does the SMF18A meet automotive transient immunity standards?
Yes, the SMF18A is explicitly validated to meet ISO 7637-2 requirements for Pulse 1, 2a, 2b, 3a, and 3b waveforms - critical for protecting electronic control units in 12 V vehicle systems. This compliance is documented in Taiwan Semiconductor's official SMF5.0A–SMF100A datasheet (Version D2103), confirming SMF18A's suitability for automotive-grade transient suppression without additional external components.
What is the maximum clamping voltage of the SMF18A during a surge event?
The SMF18A clamps to a maximum of 29.2 V when subjected to a 10/1000 µs surge waveform with a peak current of 6.8 A. This value is specified in the Electrical Specifications table of the Taiwan Semiconductor datasheet and defines the upper voltage limit imposed on protected circuitry during standardized transient events - a key parameter for ensuring downstream ICs remain within absolute maximum ratings.
Is the SMF18A RoHS and halogen-free compliant?
Yes, the SMF18A is fully RoHS compliant and halogen-free per IEC 61249-2-21. These environmental qualifications are confirmed in the Features section of the official datasheet and support compliance with global regulatory requirements for automotive and industrial electronics, including EU ELV and China RoHS directives.
What is the thermal resistance from junction to ambient for the SMF18A?
The SMF18A has a junction-to-ambient thermal resistance (RθJA) of 100 °C/W when mounted on a standard 5 mm × 5 mm copper pad PCB, as defined in the Thermal Performance section of the Taiwan Semiconductor datasheet. This value is essential for calculating steady-state junction temperature rise under continuous power dissipation and verifying safe operation within the -55 °C to +175 °C operating range.
SMF18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- SOD-123W
- Series:
- SMF
- 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):
- 6.8A
- Power - Peak Pulse:
- 200W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-123W
SMF18A FAQ
1.How can I place an order for SMF18A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF18A 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 SMF18A reliable?
The price and inventory of SMF18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF18A is usually 5 days.
3.What payment methods are accepted for SMF18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF18A?
SMF18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF18A 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 SMF18A?
For technical support, including SMF18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF18A requirements.
6.How does Aetrix verify that SMF18A is sourced from the original manufacturer or authorized distributors?
All SMF18A 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 SMF18A meets industry standards.
7.What is the process for return or replacement of SMF18A?
All SMF18A units undergo pre-shipment inspection (PSI). If there is an issue with SMF18A, 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 SMF18A part is unused and in its original packaging.
Return procedure for SMF18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF18A Tags
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