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Taiwan Semiconductor Corporation SMA4S12AH
- Part No.:
- SMA4S12AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-128
- Datasheet:
-
SMA4S12AH.pdf
- Description:
- TVS DIODE 12VWM 19.5VC SOD128
- Quantity:
- Payment:
- Shipping:
Inventory:6,871
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Product details
Overview
SMA4S12AH from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for overvoltage protection in automotive and industrial power rails. It features a 12 V working stand-off voltage (VWM), 13.4–14.8 V breakdown voltage (VBR) at 1 mA, 19.5 V clamping voltage (VC) at 20.5 A peak pulse current, and 400 W peak pulse power rating with 10/1000 µs waveform - deployed in BLDC motor drives and battery management systems.
For engineers reviewing the SMA4S12AH datasheet, SMA4S12AH pinout, SMA4S12AH application, or SMA4S12AH equivalent, key selection criteria include unidirectional polarity, SOD-128 package thermal performance (RθJL = 20 °C/W), AEC-Q101 qualification, and verified clamping behavior under repetitive surge stress.
Technical Context
The SMA4S12AH operates as a silicon avalanche diode with glass-passivated junction, optimized for fast response to transient overvoltages exceeding its VBR threshold. Its unidirectional configuration enables reverse-biased clamping only, with forward voltage of 3.5 V at 25 A, supporting DC rail protection without forward conduction interference.
Thermal design relies on low RθJL (20 °C/W) and RθJC (16 °C/W) values measured on a 5 mm × 5 mm copper pad PCB, enabling sustained 7.5 W steady-state dissipation and safe operation up to 175 °C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 12 V - maximum continuous reverse operating voltage before clamping initiates |
| VBR @ IT=1 mA | 13.4–14.8 V - precise avalanche onset range defining protection threshold accuracy |
| VC @ IPPM=20.5 A | 19.5 V - clamped voltage during 10/1000 µs surge, limiting downstream component stress |
| PPPM | 400 W - peak transient power handling capability per standard IEC 61000-4-5 surge test profile |
| TJ max | +175 °C - extended junction temperature rating enabling under-hood automotive deployment |
| RθJL | 20 °C/W - low junction-to-lead thermal resistance supports high-power pulse energy dissipation |
| Polarity | Unidirectional - protects against negative transients only; requires correct orientation in circuit |
Pinout & Package
Package: SOD-128 - surface-mount, flat-lead, single-diode outline with cathode band marking; 0.028 g mass; UL 94V-0 molding compound; matte tin-plated leads compliant with J-STD-002 solderability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input reference node for unidirectional clamping | Connected to protected line; conducts only during forward-biased surges (e.g., ESD events) |
| Cathode | Clamp return path to ground or lower potential rail | Provides low-impedance path to shunt surge current away from sensitive ICs when Vreverse > VBR |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and mechanical shock per stress test plan |
| Glass-passivated junction | Enhances long-term stability and moisture resistance versus epoxy-passivated alternatives |
| VBR tempco ≤ 0.095%/°C | Minimizes drift in clamping threshold across -55°C to +175°C operating range |
| Moisture sensitivity level 1 | Enables standard SMT reflow without baking preconditioning per J-STD-020 |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU environmental requirements |
Applications
| BLDC Motor Drive Protection | Battery Management System (BMS) |
|---|---|
Use Scenario: Suppresses inductive kickback and load dump transients in 12 V automotive BLDC gate driver power rails. IC Role / Device Role / Timing Role: TVS diode placed across MOSFET half-bridge supply input to clamp voltage spikes before they reach gate drivers or MCU power pins. Use Value: Limits transient voltage to ≤19.5 V at 20.5 A, preventing latch-up or permanent damage to 20 V-rated gate drivers and logic ICs. | Use Scenario: Protects cell monitoring ICs and communication interfaces in 12 V Li-ion battery packs during charge/discharge switching events. IC Role / Device Role / Timing Role: Unidirectional TVS installed between battery positive terminal and BMS analog front-end to absorb reverse-polarity connection surges and hot-swap transients. Use Value: Withstands 400 W peak pulses while maintaining <1 µA leakage at 12 V, ensuring minimal impact on battery self-discharge and measurement accuracy. |
| Automotive Lighting Module | Switching Mode Power Supply (SMPS) |
Use Scenario: Guards LED driver ICs against load dump and ISO 7637-2 Pulse 5a transients in headlamp control units. IC Role / Device Role / Timing Role: Mounted directly at input filter stage of buck converter powering high-intensity LEDs. Use Value: Clamps 12 V system surges to 19.5 V within nanoseconds, preserving PWM controller integrity and avoiding false shutdowns. | Use Scenario: Safeguards primary-side controller ICs and rectifier diodes in offline AC/DC adapters subjected to lightning-induced surges. IC Role / Device Role / Timing Role: Placed across bulk capacitor input to clamp differential-mode transients entering via AC line or DC bus. Use Value: Delivers 400 W pulse power handling with 20.5 A peak current capacity, meeting IEC 61000-4-5 Level 4 immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMCJ12A | Higher PPPM (1500 W), larger SMC (DO-214AB) package, higher VC (20.1 V) | Better suited for higher-energy surges but requires more PCB area and has slower response due to higher junction capacitance | Select when surge energy exceeds 400 W or when board layout allows larger footprint |
| SAC12 | Same SOD-128 package, lower PPPM (200 W), lower VBR tolerance (13.3–14.7 V), no AEC-Q101 qualification | Limited to non-automotive industrial use; lacks automotive reliability validation and thermal derating margin | Acceptable for cost-sensitive consumer-grade SMPS where AEC-Q101 is not mandated |
Compared with SMCJ12A and SAC12, the SMA4S12AH delivers optimal balance of compact SOD-128 footprint, AEC-Q101 compliance, and 400 W surge capability - making it preferred for space-constrained automotive modules requiring validated reliability and precise clamping.
Availability
SMA4S12AH is available at Aetrix Electronics and suitable for BLDC motor drives, battery management systems, automotive lighting modules, and switching mode power supplies requiring stable component supply across production lifecycles.
Supply support for SMA4S12AH 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 SMA4SxxAH series was developed specifically for AEC-Q101-compliant transient suppression in 12–60 V automotive and industrial power systems, emphasizing thermal robustness, tight VBR tolerance, and SMT manufacturability.
FAQ
What is the clamping voltage of SMA4S12AH at its rated peak pulse current?
The SMA4S12AH exhibits a maximum clamping voltage (VC) of 19.5 V when subjected to its rated peak pulse current of 20.5 A under the standard 10/1000 µs waveform. This value is measured at TA = 25°C and defines the upper voltage limit imposed on protected circuitry during surge events. The SMA4S12AH maintains this clamping performance across its specified junction temperature range, supporting reliable overvoltage protection in demanding environments.
Is SMA4S12AH qualified for automotive applications?
Yes, the SMA4S12AH is AEC-Q101 qualified, confirming its suitability for automotive electronic systems. This qualification includes rigorous testing for temperature cycling, high-temperature reverse bias (HTRB), and mechanical shock, ensuring reliability in under-hood and chassis-mounted applications. The SMA4S12AH's -55°C to +175°C operating range and SOD-128 package construction further support its deployment in automotive BLDC drives, lighting, and BMS subsystems.
What is the polarity configuration of SMA4S12AH?
The SMA4S12AH is a unidirectional TVS diode, meaning it functions as a reverse-biased avalanche device that clamps only when the cathode is at a higher potential than the anode. Its forward voltage is 3.5 V at 25 A, allowing limited forward conduction during positive transients. Correct orientation - with cathode tied to the protected line and anode to ground - is essential for proper operation. The cathode band marking on the SOD-128 package identifies terminal polarity.
How does the thermal performance of SMA4S12AH compare to similar SOD-128 TVS diodes?
The SMA4S12AH achieves RθJL = 20 °C/W and RθJC = 16 °C/W when mounted on a 5 mm × 5 mm copper pad PCB - among the lowest thermal resistances in its SOD-128 class. This enables superior heat transfer from junction to lead and case, supporting higher pulse repetition rates and longer surge endurance compared to alternatives with higher Rθ values. These metrics are verified per JEDEC test conditions and directly impact steady-state power dissipation (7.5 W) and junction temperature limits (+175°C).
What packaging and reel quantity is offered for SMA4S12AH?
The SMA4S12AH is supplied in SOD-128 package format on tape-and-reel, with 14,000 units per reel. This packaging supports high-speed automated placement in SMT assembly lines and complies with EIA-481 standards. The matte tin-plated leads meet J-STD-002 solderability requirements, and the moisture sensitivity level (MSL) is rated Level 1 - permitting indefinite floor life without dry-pack or baking prior to reflow.
SMA4S12AH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- SOD-128
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 12V
- Voltage - Breakdown (Min):
- 13.4V
- Voltage - Clamping (Max) @ Ipp:
- 19.5V
- Current - Peak Pulse (10/1000µs):
- 20.5A
- 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:
- SOD-128
SMA4S12AH FAQ
1.How can I place an order for SMA4S12AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA4S12AH 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 SMA4S12AH reliable?
The price and inventory of SMA4S12AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA4S12AH is usually 5 days.
3.What payment methods are accepted for SMA4S12AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA4S12AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA4S12AH?
SMA4S12AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA4S12AH 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 SMA4S12AH?
For technical support, including SMA4S12AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA4S12AH requirements.
6.How does Aetrix verify that SMA4S12AH is sourced from the original manufacturer or authorized distributors?
All SMA4S12AH 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 SMA4S12AH meets industry standards.
7.What is the process for return or replacement of SMA4S12AH?
All SMA4S12AH units undergo pre-shipment inspection (PSI). If there is an issue with SMA4S12AH, 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 SMA4S12AH part is unused and in its original packaging.
Return procedure for SMA4S12AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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