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Taiwan Semiconductor Corporation SMA4F18AH
- Part No.:
- SMA4F18AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-221AC, SMA Flat Leads
- Datasheet:
-
SMA4F18AH.pdf
- Description:
- 400W, 21.2V, 5%, UNIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:7,571
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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 BLDC motor drives and automotive battery management systems.
For engineers reviewing the SMA4F18AH datasheet, SMA4F18AH pinout, SMA4F18AH application, or SMA4F18AH equivalent, key selection criteria include its AEC-Q101 qualification, 175°C max junction temperature, Thin SMA package thermal performance (RθJL = 20°C/W), and unidirectional polarity for DC rail protection.
Technical Context
This TVS diode employs a glass-passivated silicon junction optimized for fast response to transients up to 10/1000μs waveform, delivering 400W non-repetitive peak pulse power dissipation. Its unidirectional configuration enables integration into DC power rails where reverse blocking is required.
Thermal design is supported by validated junction-to-lead resistance of 20°C/W on a 5mm × 5mm copper pad PCB, enabling reliable operation up to 175°C junction temperature. Moisture sensitivity level 1 ensures compatibility with standard SMT reflow processes without baking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous DC or RMS voltage the device blocks without conduction |
| VBR @ IT=1mA | 20.1–22.2 V - Verified breakdown range ensuring reliable triggering above normal operating voltage |
| VC @ IPPM=13.7A | 29.2 V - Clamped voltage during 10/1000μs surge, limiting downstream component 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 copper |
| TJ max | +175 °C - Maximum allowable junction temperature supporting under-hood automotive use |
| Polarity | Unidirectional - Blocks reverse voltage; suited for DC supply line protection |
Pinout & Package
Thin SMA package: surface-mount, single-diode, unidirectional configuration with cathode band marking. Dimensions conform to JEDEC DO-214AC outline; leads are matte tin-plated, solderable per J-STD-002.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input side of protected DC rail | Connected to power source or upstream node; conducts during forward surge events |
| Cathode | Output side / ground reference | Marked by band; ties to system ground or low-impedance return path for clamping |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing |
| Glass passivated junction | Enhances long-term stability and reduces leakage drift under high humidity or thermal stress |
| VBR tempco ≤ 0.095%/°C | Minimizes breakdown voltage shift across -55°C to +175°C operating range |
| Moisture sensitivity level 1 | Eliminates pre-bake requirement for SMT assembly, reducing manufacturing overhead |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS directives for environmentally constrained applications |
Applications
| BLDC Motor Drive Protection | Automotive Battery Management |
|---|---|
Use Scenario: Suppresses inductive kickback and load dump transients in 12–24V BLDC gate driver and power stage circuits. IC Role / Device Role / Timing Role: Unidirectional TVS placed across DC bus or MOSFET drain-source to clamp surges within 1ns response time. Use Value: Limits clamped voltage to 29.2V at 13.7A, protecting 30V-rated gate drivers and MCU I/O from damage. | Use Scenario: Guards BMS front-end analog monitoring inputs and CAN transceiver power rails against jump-start and alternator load dump. IC Role / Device Role / Timing Role: Standoff-rated TVS on 18V auxiliary supply rail, triggered only during >20.1V transients. Use Value: AEC-Q101 qualification and 175°C rating ensure robustness in engine compartment environments. |
| LED Driver Power Input | Industrial SMPS Output Rail |
Use Scenario: Protects constant-current LED driver ICs from line transients induced by nearby relay switching or EMI coupling. IC Role / Device Role / Timing Role: Mounted at DC input filter stage to absorb 400W pulses before reaching bulk capacitor and controller. Use Value: 29.2V clamping prevents overvoltage on 24V-input LED controllers while maintaining low leakage (<1µA at 18V). | Use Scenario: Shields secondary-side synchronous rectifiers and output capacitors in 18V-output AC/DC adapters. IC Role / Device Role / Timing Role: Unidirectional TVS on regulated output rail, absorbing reflected spikes from transformer leakage inductance. Use Value: Thin SMA footprint allows placement near connector or output terminal with minimal trace inductance. |
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 | Same 18V VWM, but 400W PPPM achieved at lower IPPM (22.5A); higher VC = 32.4V | Less effective clamping margin for 30V-rated downstream ICs | Prefer SMA4F18AH when tighter clamping (29.2V vs. 32.4V) is critical for 30V-system protection |
| SMBJ18A | Higher power rating (600W), larger SMB package (5.3mm × 4.6mm vs. SMA's 4.6mm × 2.8mm) | Requires PCB layout change; unsuitable for space-constrained automotive modules | Choose SMBJ18A only if 600W surge margin is required and board area permits larger footprint |
Compared with SMAJ18A and SMBJ18A, the SMA4F18AH delivers superior clamping performance in a smaller Thin SMA package while meeting AEC-Q101-making it optimal for space- and voltage-margin-sensitive automotive and BLDC designs.
Availability
SMA4F18AH is available at Aetrix Electronics and suitable for BLDC motor control, automotive battery management, and industrial SMPS applications requiring stable component supply, AEC-Q101 compliance, and compact surface-mount TVS protection.
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 automotive qualification capabilities.
The SMA4FxxAH series was developed specifically for AEC-Q101-compliant transient suppression in automotive and industrial DC power systems, emphasizing thermal robustness, tight parameter distribution, and SMT manufacturability.
FAQ
What is the maximum clamping voltage of the SMA4F18AH under a 10/1000μs surge?
The SMA4F18AH has a maximum clamping voltage (VC) of 29.2 V when subjected to its rated peak pulse current of 13.7 A with a 10/1000μs waveform. This value is measured per JEDEC standards and ensures predictable overvoltage limiting for downstream 30V-rated components. The SMA4F18AH maintains this clamping performance across its full operating temperature range.
Is the SMA4F18AH suitable for automotive applications?
Yes, the SMA4F18AH is AEC-Q101 qualified and rated for junction temperatures up to +175°C, making it suitable for under-hood and battery-related automotive applications. Its glass-passivated junction, moisture sensitivity level 1, and halogen-free construction meet stringent automotive reliability and environmental requirements. The SMA4F18AH is explicitly referenced in TSC's automotive-grade TVS portfolio.
What is the polarity configuration of the SMA4F18AH?
The SMA4F18AH is a unidirectional TVS diode, meaning it functions as a reverse-biased Zener-like clamp for positive transients on DC lines while blocking reverse voltage. The cathode is marked by a band on the Thin SMA package body. This configuration is ideal for protecting regulated DC rails where reverse conduction must be prevented.
How does the thermal performance of the SMA4F18AH compare to standard SMA packages?
The SMA4F18AH uses a Thin SMA package with a junction-to-lead thermal resistance (RθJL) of 20°C/W-lower than typical standard SMA devices (~25–30°C/W)-due to optimized internal leadframe design. When mounted on a 5mm × 5mm copper pad, this enables higher sustained power handling and improved reliability in thermally demanding layouts.
What marking code identifies the SMA4F18AH on the device body?
The SMA4F18AH is marked with the code "4F018" on its package body, followed by date and factory codes. This marking aligns with TSC's standardized coding scheme for the SMA4FxxAH family and allows field verification of voltage rating and product version (C2103). The cathode band is located adjacent to the marking.
SMA4F18AH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-221AC, SMA Flat Leads
- Series:
- SMA4F
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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 FAQ
1.How can I place an order for SMA4F18AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA4F18AH 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 reliable?
The price and inventory of SMA4F18AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA4F18AH is usually 5 days.
3.What payment methods are accepted for SMA4F18AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA4F18AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA4F18AH?
SMA4F18AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA4F18AH 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?
For technical support, including SMA4F18AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA4F18AH requirements.
6.How does Aetrix verify that SMA4F18AH is sourced from the original manufacturer or authorized distributors?
All SMA4F18AH 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 meets industry standards.
7.What is the process for return or replacement of SMA4F18AH?
All SMA4F18AH units undergo pre-shipment inspection (PSI). If there is an issue with SMA4F18AH, 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 part is unused and in its original packaging.
Return procedure for SMA4F18AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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