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Taiwan Semiconductor Corporation SMA4S20AH
- Part No.:
- SMA4S20AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-128
- Datasheet:
-
SMA4S20AH.pdf
- Description:
- TVS DIODE 20VWM 32.5VC SOD128
- Quantity:
- Payment:
- Shipping:
Inventory:8,939
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Product details
Overview
SMA4S20AH from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode with a 20V working stand-off voltage, 22.4–24.7V breakdown voltage at 1mA, and 32.5V clamping voltage at 12.3A peak pulse current; used for overvoltage protection in automotive BLDC motor drives and battery management systems.
For engineers reviewing the SMA4S20AH datasheet, SMA4S20AH pinout, SMA4S20AH application, or SMA4S20AH equivalent, key selection criteria include unidirectional polarity, SOD-128 package thermal performance (RθJL = 20°C/W), 175°C max junction temperature, and AEC-Q101 qualification for automotive-grade reliability.
Technical Context
The SMA4S20AH operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its 22.4–24.7V breakdown range, clamping transients to ≤32.5V at 12.3A (10/1000μs waveform). Its glass-passivated junction ensures stable VBR temperature coefficient of 0.095%/°C and supports operation from –55°C to +175°C.
Designed for PCB-level surge suppression, it delivers 400W non-repetitive peak pulse power with thermal resistance RθJA = 62°C/W on a 5mm × 5mm copper pad, enabling robust protection in space-constrained automotive and industrial power stages without external heat sinking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 20 V - Maximum continuous reverse operating voltage before conduction begins |
| VBR @ IT=1mA | 22.4–24.7 V - Validated avalanche onset range ensuring reliable triggering margin above VWM |
| VC @ IPPM=12.3A | 32.5 V - Clamped voltage during 400W transient, limiting downstream IC stress |
| PPPM | 400 W - Peak pulse power handling per 10/1000μs waveform, per IEC 61000-4-5 Level 4 |
| TJ max | +175 °C - Enables placement near hot components (e.g., MOSFETs, gate drivers) in motor control PCBs |
| RθJL | 20 °C/W - Low junction-to-lead thermal resistance supports high-power pulse dissipation into PCB copper |
Pinout & Package
Package: SOD-128 - Surface-mount plastic case with matte tin-plated leads, UL 94V-0 rated molding compound, and cathode band marking. Weight: 0.028 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current path / low-side reference node | Connected to ground or low-impedance return path; defines unidirectional conduction direction |
| Cathode | Protected line input / high-side connection | Connected to the line being protected (e.g., motor phase, battery rail); carries clamped transient current |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control, BLDC drives, and BMS under stress conditions |
| Glass passivated junction | Ensures long-term stability of VBR and leakage (<1 µA @ 20V) across temperature and lifetime |
| VBR tempco: 0.095%/°C | Minimizes drift in trigger threshold across –55°C to +175°C, critical for wide-temperature automotive use |
| Moisture sensitivity level 1 | Enables standard SMT reflow without baking, reducing manufacturing complexity and cost |
Applications
| BLDC Motor Drive Protection | Battery Management System (BMS) |
|---|---|
Use Scenario: Suppresses inductive kickback and load dump transients on 24V BLDC motor phase lines in automotive HVAC or power steering modules. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed across motor winding terminals to clamp voltage spikes to ≤32.5V. Use Value: Prevents gate oxide damage to 40V-rated MOSFETs and maintains functional safety integrity per ISO 26262 ASIL-B requirements. | Use Scenario: Protects cell monitoring ICs and coulomb counter inputs from ESD and load dump events on 20V nominal Li-ion battery packs. IC Role / Device Role / Timing Role: Standoff protector on analog front-end inputs, leveraging 20V VWM to avoid false triggering during normal pack operation. Use Value: Maintains <1 µA leakage at 20V, preserving measurement accuracy and minimizing self-discharge in always-on BMS circuits. |
| Automotive Lighting Control | Industrial SMPS Input Stage |
Use Scenario: Shields LED driver ICs from alternator-induced surges and relay-switching transients in headlamp control units. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 20V auxiliary supply rail feeding buck controllers and CAN transceivers. Use Value: Withstands 400W pulses while maintaining 175°C junction rating, eliminating need for derating in sealed headlamp enclosures. | Use Scenario: Safeguards AC-DC PFC stage outputs and DC-DC converter inputs against lightning-induced surges in DIN-rail mounted power supplies. IC Role / Device Role / Timing Role: Secondary-side transient suppressor on 20V bias rails feeding gate drivers and optocouplers. Use Value: Delivers 62°C/W RθJA on standard PCB layout, enabling reliable 400W pulse handling without heatsink or airflow dependency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ20A | Same SOD-128 package, 20V VWM, but lower PPPM (400W same), higher VC (34.0V vs. 32.5V) | Marginally reduced clamping performance may require downstream component voltage derating | Acceptable where 1.5V higher clamping is tolerable and Littelfuse supply chain preference applies |
| ON Semiconductor SMA6J20A | Identical VWM/VBR/VC specs, but not AEC-Q101 qualified; RθJA = 65°C/W (vs. 62°C/W) | Lacks automotive qualification; thermal margin slightly reduced on identical PCB layout | Preferred for industrial SMPS where AEC-Q101 is unnecessary and ON Semi sourcing is prioritized |
Compared with SMAJ20A and SMA6J20A, the SMA4S20AH provides tighter clamping (32.5V), superior thermal resistance (62°C/W), and mandatory AEC-Q101 compliance-making it the optimal choice for automotive BLDC and BMS designs requiring validated reliability and minimal voltage overshoot.
Availability
SMA4S20AH is available at Aetrix Electronics and suitable for automotive BLDC motor drives, battery management systems, and industrial switching mode power supplies requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SMA4S20AH 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 SMA4SxxAH series was developed specifically for automotive-grade transient suppression in high-reliability 12–60V systems, emphasizing thermal robustness, low leakage, and consistent clamping performance across temperature.
FAQ
What is the maximum clamping voltage of the SMA4S20AH under a 10/1000μs transient?
The SMA4S20AH has a maximum clamping voltage (VC) of 32.5 V when subjected to a 12.3 A peak pulse current with a 10/1000 μs waveform. This value is measured per IEC 61000-4-5 test conditions and ensures downstream components see limited overvoltage stress. The SMA4S20AH achieves this clamping performance while maintaining its 400W peak pulse rating and unidirectional polarity configuration.
Is the SMA4S20AH qualified for automotive applications?
Yes, the SMA4S20AH is AEC-Q101 qualified, confirming its suitability for automotive environments including powertrain, chassis, and body electronics. It meets stress tests for temperature cycling, humidity, mechanical shock, and high-temperature operating life. This qualification is explicitly stated in the official Taiwan Semiconductor datasheet (Version C2103) and applies directly to the SMA4S20AH device, not just the family.
What is the thermal resistance from junction to ambient for the SMA4S20AH?
The junction-to-ambient thermal resistance (RθJA) of the SMA4S20AH is 62°C/W when mounted on a standard 5 mm × 5 mm copper pad test board. This value enables effective heat dissipation during repetitive or high-energy transients. The SMA4S20AH also features RθJL = 20°C/W, supporting efficient thermal transfer into PCB traces and internal lead frames.
Does the SMA4S20AH have unidirectional or bidirectional polarity?
The SMA4S20AH is a unidirectional TVS diode, as confirmed by its polarity marking (cathode band), forward voltage specification (VF = 3.5 V @ 25 A), and electrical test conditions referencing unidirectional blocking behavior. Its datasheet specifies "Polarity: Uni-directional" under Mechanical Data and lists only reverse-biased parameters (VWM, VBR, VC) - no symmetrical bidirectional characteristics are defined for the SMA4S20AH.
What is the moisture sensitivity level (MSL) of the SMA4S20AH?
The SMA4S20AH has a moisture sensitivity level (MSL) of Level 1 per J-STD-020, meaning it can be stored indefinitely at ≤30°C/85% RH and is compatible with standard SMT reflow profiles without pre-baking. This MSL rating is documented in the official Taiwan Semiconductor datasheet and applies specifically to the SMA4S20AH in SOD-128 packaging.
SMA4S20AH 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):
- 20V
- Voltage - Breakdown (Min):
- 22.4V
- Voltage - Clamping (Max) @ Ipp:
- 32.5V
- Current - Peak Pulse (10/1000µs):
- 12.3A
- 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
SMA4S20AH FAQ
1.How can I place an order for SMA4S20AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA4S20AH 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 SMA4S20AH reliable?
The price and inventory of SMA4S20AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA4S20AH is usually 5 days.
3.What payment methods are accepted for SMA4S20AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA4S20AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA4S20AH?
SMA4S20AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA4S20AH 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 SMA4S20AH?
For technical support, including SMA4S20AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA4S20AH requirements.
6.How does Aetrix verify that SMA4S20AH is sourced from the original manufacturer or authorized distributors?
All SMA4S20AH 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 SMA4S20AH meets industry standards.
7.What is the process for return or replacement of SMA4S20AH?
All SMA4S20AH units undergo pre-shipment inspection (PSI). If there is an issue with SMA4S20AH, 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 SMA4S20AH part is unused and in its original packaging.
Return procedure for SMA4S20AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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