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Taiwan Semiconductor Corporation SMA4F18AH MWG
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- Part No.:
- SMA4F18AH MWG
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-221AC, SMA Flat Leads
- Datasheet:
-
SMA4F18AH MWG.pdf
- Description:
- 400W, 17.65V, 5%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:3,714
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Product details
Overview
SMA4F18AH from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode with a 18V working stand-off voltage, 20.1–22.2V breakdown voltage at 1mA, and 29.2V clamping voltage at 13.7A peak pulse current; used for overvoltage protection in automotive BLDC motor drives and battery management systems.
For engineers reviewing the SMA4F18AH datasheet, SMA4F18AH pinout, SMA4F18AH application, or SMA4F18AH equivalent, key selection criteria include unidirectional polarity, Thin SMA package thermal performance (RθJL = 20°C/W), AEC-Q101 qualification, and verified 175°C maximum junction temperature operation under 10/1000µs surge conditions.
Technical Context
The SMA4F18AH operates as a unidirectional avalanche diode, designed to clamp transient overvoltages above its VBR threshold while maintaining low leakage (<1µA at 18V) and stable VBR temperature coefficient (0.095%/°C). Its glass-passivated junction ensures robust reliability under repeated surge stress.
Thermal design relies on PCB-mounted 5mm × 5mm copper pads, delivering RθJA = 62°C/W and RθJC = 16°C/W. It supports steady-state power dissipation of 7.5W at TL = 25°C and withstands junction temperatures from –55°C to +175°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before conduction begins |
| VBR @ IT = 1 mA | 20.1–22.2 V - Verified breakdown range ensuring reliable turn-on margin above VWM |
| VC @ IPPM = 13.7 A | 29.2 V - Clamped voltage during 10/1000µs surge, limiting downstream circuit stress |
| PPPM | 400 W - Peak pulse power handling capability per standard 10/1000µs waveform |
| RθJL | 20 °C/W - Junction-to-lead thermal resistance enabling efficient heat transfer to PCB traces |
| Junction Temp Range | –55°C to +175°C - Validated operating envelope for under-hood automotive environments |
Pinout & Package
Package: Thin SMA - Surface-mount plastic case with matte tin-plated leads, UL 94V-0 rated molding compound, polarity indicated by cathode band, weight ≈ 0.030 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point in forward bias | Connected to lower-potential node (e.g., ground or return path) during clamping |
| Cathode | Current exit point in forward bias; marked with band | Connected to protected line (e.g., 18V rail); defines unidirectional clamping direction |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, humidity, and mechanical shock |
| Glass passivated junction | Enhanced moisture resistance and long-term stability vs. epoxy-passivated alternatives |
| VBR tempco ≤ 0.095%/°C | Predictable breakdown shift across –40°C to +125°C ambient, critical for precision clamping |
| Moisture sensitivity level 1 | No baking required prior to reflow; compatible with standard SMT assembly processes |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS directives for environmentally constrained applications |
Applications
| BLDC Motor Drive Protection | Battery Management System (BMS) |
|---|---|
Use Scenario: Suppresses inductive kickback spikes generated during PWM switching of 18V-rated BLDC gate drivers and H-bridge outputs. IC Role / Device Role / Timing Role: Unidirectional TVS placed across motor phase lines or supply rails to clamp transients below MOSFET VDSS rating. Use Value: Limits clamping voltage to 29.2V at 13.7A, preventing gate oxide damage and ensuring >2× safety margin versus 18V nominal rail. | Use Scenario: Protects cell monitoring ICs and coulomb counter inputs from ESD and load-dump events in 12–24V battery packs. IC Role / Device Role / Timing Role: Standoff-rated TVS on analog front-end inputs and communication lines (e.g., SMBus, CAN PHY power rails). Use Value: Delivers <1µA leakage at 18V, preserving measurement accuracy while surviving 400W surges per ISO 7637-2 Pulse 5a. |
| Automotive Lighting Control | Switching Mode Power Supply (SMPS) |
Use Scenario: Shields LED driver ICs and microcontrollers from load dump and jump-start transients in headlamp and DRL modules. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 12V input stage upstream of DC-DC converters and LED current regulators. Use Value: AEC-Q101 qualification and 175°C TJMAX ensure uninterrupted operation in high-ambient under-hood lighting housings. | Use Scenario: Safeguards secondary-side rectifiers and feedback optocouplers in 18V-output flyback or forward converters. IC Role / Device Role / Timing Role: Transient suppressor on output rail and auxiliary bias winding to prevent regulation loop upset and MOSFET failure. Use Value: 29.2V clamping voltage maintains output regulation integrity during 10/1000µs surges without triggering OVP shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Lower PPPM (400W same), but higher VC = 32.4V at 12.3A; RθJA = 65°C/W | Less effective clamping margin in high-current transients; slightly reduced thermal efficiency | Acceptable where layout allows larger copper area or where 3.2V higher clamping is tolerable |
| SMBJ18A | Same VWM/VBR, but SMB package (larger footprint); PPPM = 600W; RθJA = 50°C/W | Higher surge capacity and better thermal performance, but requires PCB redesign | Preferred for industrial SMPS with frequent high-energy transients; not drop-in compatible |
Compared with SMAJ18A and SMBJ18A, the SMA4F18AH delivers tighter VBR tolerance (20.1–22.2V vs. 19.0–21.0V), lower clamping voltage (29.2V), and AEC-Q101 qualification-making it optimal for space-constrained, automotive-grade 18V rail protection without layout change.
Availability
SMA4F18AH is available at Aetrix Electronics and suitable for BLDC motor drives, battery management systems, and automotive lighting applications requiring stable component supply, AEC-Q101 compliance, and consistent Thin SMA footprint availability.
Supply support for SMA4F18AH 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, and rectifiers with global distribution and AEC-Q101 validation capability.
The SMA4FxxAH series was developed specifically for automotive and industrial transient suppression, emphasizing high surge robustness in compact Thin SMA packages with guaranteed temperature-stable breakdown behavior.
FAQ
What is the maximum clamping voltage of the SMA4F18AH under standard surge conditions?
The SMA4F18AH exhibits a maximum clamping voltage (VC) of 29.2 V when subjected to a 10/1000 µs waveform peak pulse current of 13.7 A. This value is measured per JEDEC standards and reflects the device's ability to limit transient energy delivered to downstream circuitry. The SMA4F18AH maintains this clamping performance across its full operating temperature range and is validated in production test lots per Taiwan Semiconductor's C2103 specification revision.
Is the SMA4F18AH suitable for automotive applications requiring AEC-Q101 qualification?
Yes, the SMA4F18AH is explicitly AEC-Q101 qualified per the manufacturer's documentation and test reports. It undergoes stress testing including temperature cycling, high-temperature reverse bias, and mechanical shock to meet automotive reliability requirements. The SMA4F18AH is commonly deployed in engine control units, body electronics, and ADAS subsystems where certified transient protection is mandatory-and its marking code "4F018" corresponds directly to the qualified variant in Taiwan Semiconductor's AEC-Q101 master list.
What is the thermal resistance from junction to ambient for the SMA4F18AH?
The SMA4F18AH has a junction-to-ambient thermal resistance (RθJA) of 62°C/W when mounted on a standard 5 mm × 5 mm copper pad test board. This value assumes no additional heatsinking and is critical for calculating safe power derating above 25°C ambient. For designs requiring higher sustained power, thermal modeling must account for PCB copper area, layer count, and airflow-since RθJA degrades significantly with smaller pads or no internal plane coupling.
Does the SMA4F18AH have unidirectional or bidirectional polarity?
The SMA4F18AH is a unidirectional TVS diode, indicated by its cathode band marking and specified forward voltage (VF = 3.5 V at 25 A). It conducts only during reverse overvoltage events on the cathode side and blocks normal forward-biased operation. This polarity configuration makes the SMA4F18AH appropriate for DC rail protection where polarity is fixed-such as 18V battery inputs or regulated supply lines-and distinguishes it from bidirectional variants like SMA4F18AY.
What is the moisture sensitivity level (MSL) rating for the SMA4F18AH?
The SMA4F18AH carries a moisture sensitivity level (MSL) rating of Level 1 per J-STD-020, meaning it is not sensitive to moisture-induced damage during reflow soldering and does not require dry-packaging or baking prior to assembly. This simplifies manufacturing logistics and reduces process risk in high-volume SMT lines-especially important for automotive Tier 1 suppliers using lead-free reflow profiles up to 260°C peak temperature.
SMA4F18AH MWG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-221AC, SMA Flat Leads
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20.1V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 13.7A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- Thin SMA
SMA4F18AH MWG FAQ
1.How can I place an order for SMA4F18AH MWG through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA4F18AH MWG 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 SMA4F18AH MWG reliable?
The price and inventory of SMA4F18AH MWG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA4F18AH MWG is usually 5 days.
3.What payment methods are accepted for SMA4F18AH MWG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA4F18AH MWG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA4F18AH MWG?
SMA4F18AH MWG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA4F18AH MWG 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 SMA4F18AH MWG?
For technical support, including SMA4F18AH MWG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA4F18AH MWG requirements.
6.How does Aetrix verify that SMA4F18AH MWG is sourced from the original manufacturer or authorized distributors?
All SMA4F18AH MWG 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 SMA4F18AH MWG meets industry standards.
7.What is the process for return or replacement of SMA4F18AH MWG?
All SMA4F18AH MWG units undergo pre-shipment inspection (PSI). If there is an issue with SMA4F18AH MWG, 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 SMA4F18AH MWG part is unused and in its original packaging.
Return procedure for SMA4F18AH MWG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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