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Taiwan Semiconductor Corporation SMF28AH
- Part No.:
- SMF28AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF28AH.pdf
- Description:
- TVS DIODE 28VWM 45.4VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:4,079
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Product details
Overview
SMF28AH from Taiwan Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode designed for automotive-grade circuit protection. It features a 28 V working stand-off voltage (VWM), 31.1–34.4 V breakdown voltage (VBR), 45.4 V clamping voltage (VC) at 4.4 A peak pulse current, and 200 W peak pulse power (10/1000 µs). It is AEC-Q101 qualified and used to protect CAN/LIN bus interfaces and microcontroller I/O lines against ISO 7637-2 pulses.
For engineers reviewing the SMF28AH datasheet, SMF28AH pinout, SMF28AH application, or SMF28AH equivalent, key selection criteria include clamping performance under 10/1000 µs transients, low leakage (<1 µA @ 28 V), SOD-123W package compatibility with automated assembly, and compliance with automotive EFT and load-dump immunity standards.
Technical Context
The SMF28AH operates as a unidirectional avalanche diode, conducting only in reverse bias above its breakdown threshold to shunt transient energy to ground. Its glass-passivated junction ensures stable VBR tolerance (±5%) and low leakage across temperature (–55°C to +175°C).
It delivers 200 W peak pulse power per 10/1000 µs waveform at TA = 25°C, derating linearly above 25°C per Fig.2, with thermal resistance RθJA = 100°C/W on a 5 mm × 5 mm Cu pad PCB. Clamping occurs within nanoseconds, limiting voltage overshoot to ≤45.4 V at 4.4 A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR min / max | 31.1 V / 34.4 V - Breakdown range at 1 mA test current; defines turn-on threshold consistency |
| VC @ IPPM | 45.4 V @ 4.4 A - Clamped voltage during 10/1000 µs surge; determines protected IC's maximum stress level |
| PPPM | 200 W - Peak pulse power handling capability; supports ISO 7637-2 Pulse 1/2a/2b/3a/3b immunity |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off; ensures minimal standby power loss in battery-critical systems |
| TJ max | +175 °C - Maximum junction temperature; enables operation in under-hood automotive environments |
| Package | SOD-123W - Surface-mount outline with matte tin-plated leads; compatible with J-STD-002 soldering and JESD 201 Class 2 whisker resistance |
Pinout & Package
SMF28AH uses the SOD-123W package: a compact, gull-wing surface-mount case with cathode band polarity marking and 0.016 g mass. Leads are matte tin-plated and compliant with J-STD-002 solderability requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to protected line (e.g., CAN_H); conducts during forward surge or ESD event |
| Cathode | Reverse-biased clamping terminal | Connected to ground; avalanches at VBR to clamp transients when line voltage exceeds VWM |
| Cathode band | Polarity indicator | Visible marking on package body; ensures correct orientation during automated placement and inspection |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive applications including engine control units and body electronics per stress test requirements |
| Glass-passivated junction | Ensures stable VBR over lifetime and improved humidity resistance vs. epoxy-passivated alternatives |
| ISO 7637-2 compliance | Meets Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (EFT) immunity thresholds |
| Low IR & high clamping efficiency | Leakage <1 µA @ 28 V and VC/VBR ratio of 1.31 enable robust protection without signal distortion or DC loading |
| SOD-123W mechanical robustness | UL 94V-0 molding compound and JESD 201 Class 2 whisker resistance support high-reliability industrial and automotive PCBs |
Applications
| Automotive LIN Bus Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting LIN transceivers in door modules and seat controllers from battery feed transients and ESD events. IC Role / Device Role / Timing Role: Unidirectional TVS placed between LIN bus line and ground to clamp surges before they reach the transceiver input. Use Value: Limits voltage to ≤45.4 V during 10/1000 µs pulses, preserving transceiver integrity while maintaining signal integrity due to low capacitance and leakage. | Use Scenario: Safeguarding analog output pins of pressure/temperature sensors in factory automation PLC I/O modules. IC Role / Device Role / Timing Role: Standoff protection device on 4–20 mA loop outputs, absorbing inductive kickback from solenoid drivers. Use Value: Withstands 200 W peak pulses and operates up to +175°C, enabling reliable field deployment in hot industrial enclosures. |
| Automotive Body Control Module (BCM) | Smart Lighting Driver Protection |
Use Scenario: Shielding microcontroller GPIOs and power supply rails in BCMs from load-dump events during alternator regulation faults. IC Role / Device Role / Timing Role: Primary transient suppressor on 12 V rail inputs and switch matrix sense lines. Use Value: AEC-Q101 qualification and 175°C TJ rating ensure long-term reliability in under-dash mounting locations with wide thermal cycling. | Use Scenario: Protecting LED driver ICs in adaptive headlamp systems from switching noise and ESD during assembly and operation. IC Role / Device Role / Timing Role: Reverse-biased clamping element on constant-current output stage to prevent overvoltage damage during PWM dimming transitions. Use Value: Fast response (<1 ns) and low clamping ratio (VC/VBR = 1.31) minimize voltage overshoot, preventing premature LED driver latch-up or shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A | Same VWM (28 V), but higher VC (48.4 V @ 4.3 A); SMA package (larger footprint, higher RθJA) | Less suitable for space-constrained automotive modules; lower thermal performance on small pads | Choose SMAJ28A only if board layout allows larger SMA footprint and thermal budget permits higher junction rise |
| 1.5SMC28A | Higher PPPM (1500 W), but much larger DO-214AB package; VWM identical, VC = 43.4 V @ 34.6 A | Over-specified for typical 200 W surge needs; requires significant PCB area and rework for existing SOD-123W layouts | Select 1.5SMC28A only for high-energy industrial surge environments where 200 W is insufficient |
Compared with SMAJ28A and 1.5SMC28A, the SMF28AH provides optimal balance of compact SOD-123W size, AEC-Q101 qualification, and precise 200 W/45.4 V clamping-making it ideal for automotive and space-limited industrial designs requiring verified automotive reliability without over-engineering.
Availability
SMF28AH is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, smart lighting systems, and LIN/CAN bus protection requiring stable component supply and long-term lifecycle assurance.
Supply support for SMF28AH 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 SMF series was developed specifically for AEC-Q101-compliant transient suppression in automotive ECUs and body electronics, emphasizing low-leakage, tight VBR tolerance, and robust SOD-123W packaging for automated manufacturing.
FAQ
What is the maximum clamping voltage of the SMF28AH under standard 10/1000 µs surge conditions?
The SMF28AH has a maximum clamping voltage (VC) of 45.4 V when subjected to a 10/1000 µs transient pulse at its rated peak pulse current of 4.4 A. This value is measured per JEDEC standards and confirmed in the official TSC datasheet Rev. A2103, ensuring predictable overvoltage limiting for downstream ICs such as LIN transceivers or microcontroller I/O pins.
Is the SMF28AH suitable for use in automotive applications requiring AEC-Q101 certification?
Yes, the SMF28AH is explicitly AEC-Q101 qualified per the manufacturer's documentation. It undergoes stress testing for temperature cycling, humidity, HTRB, and mechanical shock, making it suitable for under-hood and cabin-mounted automotive modules including body control units, lighting controllers, and sensor interface circuits where reliability under harsh conditions is mandatory.
What is the reverse leakage current specification for SMF28AH at its working stand-off voltage?
The SMF28AH exhibits a maximum reverse leakage current (IR) of less than 1 µA when biased at its 28 V working stand-off voltage (VWM), tested at TA = 25°C. This ultra-low leakage preserves battery life in always-on automotive subsystems and prevents false triggering in high-impedance sensor signal paths.
Does the SMF28AH have polarity marking, and how is it identified on the package?
Yes, the SMF28AH uses a cathode band to indicate polarity - a visible dark band near one end of the SOD-123W package body. This band identifies the cathode terminal, which must be connected to ground for proper unidirectional clamping operation. The anode is the opposite lead, and the marking code "2W028" appears adjacent to the cathode band.
What is the thermal resistance from junction to ambient (RθJA) for SMF28AH, and under what conditions is it measured?
The SMF28AH has a junction-to-ambient thermal resistance (RθJA) of 100°C/W, measured with the device mounted on a standard 5 mm × 5 mm copper pad PCB per JESD51-3. This value supports thermal design in compact automotive modules, though actual performance improves with additional copper pour or thermal vias in production layouts.
SMF28AH 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):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- Power - Peak Pulse:
- 200W
- 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:
- SOD-123W
SMF28AH FAQ
1.How can I place an order for SMF28AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF28AH 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 SMF28AH reliable?
The price and inventory of SMF28AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF28AH is usually 5 days.
3.What payment methods are accepted for SMF28AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF28AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF28AH?
SMF28AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF28AH 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 SMF28AH?
For technical support, including SMF28AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF28AH requirements.
6.How does Aetrix verify that SMF28AH is sourced from the original manufacturer or authorized distributors?
All SMF28AH 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 SMF28AH meets industry standards.
7.What is the process for return or replacement of SMF28AH?
All SMF28AH units undergo pre-shipment inspection (PSI). If there is an issue with SMF28AH, 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 SMF28AH part is unused and in its original packaging.
Return procedure for SMF28AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF28AH Tags
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