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Taiwan Semiconductor Corporation SMAJ20A
- Part No.:
- SMAJ20A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ20A.pdf
- Description:
- TVS DIODE 20VWM 32.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,480
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Product details
Overview
SMAJ20A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for clamping fast transients in DC power lines. It features a 20 V working stand-off voltage (VWM), 22.2–24.5 V breakdown voltage (VBR @ 1 mA), and clamps to ≤32.4 V at 12.3 A peak impulse current under 10/1000 µs waveform - delivering 400 W peak pulse power for automotive and industrial power supply protection.
For engineers reviewing the SMAJ20A datasheet, SMAJ20A pinout, SMAJ20A application, or SMAJ20A equivalent, this device is selected for robust overvoltage protection in SMPS inputs, DC/DC converters, and lighting drivers where low clamping voltage, sub-1 ps response, and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance are required.
Technical Context
The SMAJ20A operates as a unidirectional avalanche diode with glass-passivated junction, enabling fast response (<1.0 ps from 0 V to VBR min) and stable clamping under repetitive surge stress. Its thermal design supports continuous operation up to +150 °C junction temperature and meets JESD201 Class 2 whisker resistance and J-STD-020 Level 1 moisture sensitivity.
It delivers 400 W peak pulse power (10/1000 µs) at 25 °C, derating linearly above ambient - sustaining 300 W above 78 V VWM. The device exhibits <1 µA reverse leakage at 20 V and a maximum forward voltage of 3.5 V at 25 A, confirming suitability for high-reliability DC rail protection without forward conduction interference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 20 V - Maximum continuous DC or RMS voltage the device blocks without clamping; sets operating margin before transient activation. |
| VBR @ IT=1 mA | 22.2–24.5 V - Verified avalanche onset range; ensures predictable turn-on during ESD/EFT events above stand-off threshold. |
| VC @ IPPM=12.3 A | ≤32.4 V - Clamped voltage under 10/1000 µs surge; limits downstream IC stress to safe levels in 24 V systems. |
| PPPM | 400 W - Peak pulse power handling per single 10/1000 µs transient; sufficient for ISO 7637-2 Pulse 1 (inductive load dump) and Pulse 2b (battery disconnect). |
| IR @ VWM | <1 µA - Ultra-low leakage at rated stand-off; prevents parasitic loading in high-impedance sensing or battery-backed circuits. |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline with 0.060 g mass, UL 94V-0 molding, and matte tin-plated leads compliant with J-STD-002 solderability. |
| Operating TJ | −55 to +150 °C - Wide junction temperature range enables deployment in under-hood automotive, industrial controls, and outdoor LED drivers. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with axial cathode band marking; two terminals - anode and cathode - mounted on standard 2.54 mm pitch PCB pads per manufacturer's suggested layout. Cathode band denotes polarity for unidirectional operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point during forward conduction or clamping | Connected to protected line (e.g., +24 V rail); carries surge current into device during reverse-biased transient clamping. |
| Cathode | Current exit point; marked by band | Connected to ground or lower-potential reference; defines clamping direction and ensures correct orientation in series protection paths. |
Key Features
| Feature | Design Value |
|---|---|
| Clamping voltage ≤32.4 V at 12.3 A | Enables reliable protection of 24 V logic and power ICs (e.g., MCUs, gate drivers) without exceeding absolute maximum ratings. |
| Response time <1.0 ps | Activates faster than most system-level transients (e.g., ESD, relay bounce), minimizing voltage overshoot before suppression engages. |
| ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance | Validated for automotive power network immunity - critical for ECUs, body control modules, and infotainment power supplies. |
| RoHS & halogen-free (IEC 61249-2-21) | Meets global environmental regulations and enables use in consumer, medical, and industrial products requiring green material declarations. |
| Moisture sensitivity level 1 (J-STD-020) | Eliminates bake requirements prior to reflow; supports standard SMT assembly without special handling or floor-life constraints. |
Applications
| Automotive Body Control Module (BCM) | Industrial 24 V DC/DC Converter Input |
|---|---|
Use Scenario: Protects microcontroller I/O and CAN transceiver power rails from load-dump transients and battery disconnect spikes in vehicle BCMs. IC Role / Device Role / Timing Role: Unidirectional TVS placed between +12 V/+24 V supply and chassis ground to clamp surges before they reach LDOs and communication ICs. Use Value: Limits clamped voltage to ≤32.4 V, staying well below 36 V absolute max ratings of common 24 V-rated automotive MCUs and transceivers. |
Use Scenario: Shields isolated DC/DC converter primary-side input against switching noise, lightning-induced surges, and inductive kickback in factory automation PLCs. IC Role / Device Role / Timing Role: Standoff protector on 24 V input bus, absorbing repetitive 400 W pulses without degradation across 10⁵+ cycles. Use Value: Maintains <1 µA leakage at 20 V, avoiding efficiency loss in low-power standby modes while surviving 150 °C ambient operation near heatsinks. |
| LED Streetlight Driver Input Stage | Medical Equipment Power Supply Ingress |
Use Scenario: Guards constant-current LED driver front-end against grid surges and nearby lightning coupling in outdoor streetlight installations. IC Role / Device Role / Timing Role: First-line transient suppressor on AC-DC rectified output or DC bus, placed upstream of bulk capacitors and PWM controllers. Use Value: Delivers 400 W peak power handling with 32.4 V clamping, ensuring downstream MOSFETs and current-sense amplifiers remain within SOA during 10/1000 µs surges. |
Use Scenario: Secures auxiliary 24 V supply rail in diagnostic imaging equipment against ESD and conducted transients per IEC 61000-4-4/5. IC Role / Device Role / Timing Role: Unidirectional clamping element on isolated secondary-side power, meeting safety isolation and low-leakage requirements. Use Value: Complies with halogen-free and RoHS mandates while providing sub-1 ps response - critical for protecting sensitive analog front-ends and ADC references. |
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 | Identical electrical specs (VWM=20 V, VC≤32.4 V @12.3 A), same DO-214AC package, but rated for 150 °C TJ max and meets AEC-Q200 Grade 2. | Qualified for automotive under-hood use; preferred when AEC-Q200 qualification is mandatory. | Select Littelfuse SMAJ20A if AEC-Q200 compliance is required; Taiwan Semiconductor SMAJ20A is suitable for industrial and commercial applications with identical clamping performance. |
| ON Semiconductor SMAJ20A | Same VWM, VBR, and VC specs; identical 400 W rating; differs in IR spec - max 5 µA @ VWM vs. Taiwan Semiconductor's <1 µA. | Higher leakage may affect ultra-low-power standby circuits; otherwise functionally interchangeable in most 24 V power rails. | Choose Taiwan Semiconductor SMAJ20A for designs requiring <1 µA leakage; ON Semi version acceptable where leakage tolerance >5 µA is permitted. |
Compared with Littelfuse and ON Semiconductor SMAJ20A variants, Taiwan Semiconductor SMAJ20A offers tighter reverse leakage (<1 µA), identical clamping performance, and full ISO 7637-2 compliance - making it optimal for precision 24 V systems where leakage-sensitive bias networks or long battery backup durations are critical.
Availability
SMAJ20A is available at Aetrix Electronics and suitable for automotive body control modules, industrial 24 V DC/DC converters, and outdoor LED lighting drivers requiring stable component supply, consistent parametric performance, and full traceability across production lots.
Supply support for SMAJ20A 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 - serving industrial, automotive, and consumer markets since 1979.
The SMAJ series is part of TSC's transient protection product line, engineered specifically for high-energy surge suppression in harsh environments - emphasizing low clamping voltage, fast response, and automotive-grade reliability without premium cost.
FAQ
What is the maximum clamping voltage of SMAJ20A under standard test conditions?
The SMAJ20A has a maximum clamping voltage (VC) of 32.4 V when subjected to a 10/1000 µs waveform at 12.3 A peak impulse current (IPPM). This value is measured per JEDEC standards and confirmed in Taiwan Semiconductor's U2102 datasheet - ensuring predictable voltage limiting for 24 V system components during surge events. The SMAJ20A maintains this clamping performance across its full operating temperature range.
Is SMAJ20A unidirectional or bidirectional, and how is polarity identified?
SMAJ20A is a unidirectional TVS diode, meaning it clamps only in reverse bias and conducts forward like a standard diode. Polarity is indicated by a cathode band on the DO-214AC (SMA) package body - the banded end connects to ground or the lower-potential node. This configuration protects positive-rail transients while blocking forward conduction during normal operation. SMAJ20CA would be the bidirectional variant.
Does SMAJ20A meet automotive transient immunity standards?
Yes, SMAJ20A meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a (sudden load removal), Pulse 2b (battery disconnect), and Pulses 3a/3b (switching noise). Its 400 W peak pulse power rating and sub-1 ps response ensure effective suppression of these waveforms in 12 V and 24 V automotive networks - validated per Taiwan Semiconductor's U2102 specification document.
What is the reverse leakage current specification for SMAJ20A at its working voltage?
At its 20 V working stand-off voltage (VWM), the SMAJ20A exhibits a maximum reverse leakage current (IR) of less than 1 µA at 25 °C - significantly lower than many competing TVS diodes. This ultra-low leakage minimizes power loss in always-on circuits and preserves accuracy in high-impedance monitoring paths. The SMAJ20A maintains this performance across its −55 to +150 °C operating junction temperature range.
Can SMAJ20A be used in place of SMAJ20, and what is the key difference?
Yes, SMAJ20A can replace SMAJ20 in most designs, but with improved clamping performance: SMAJ20A has a tighter breakdown voltage range (22.2–24.5 V vs. 22.2–27.1 V for SMAJ20) and lower clamping voltage (32.4 V vs. 35.8 V at rated IPPM). This makes SMAJ20A preferable for applications demanding stricter voltage margins - such as protecting 3.3 V or 5 V logic powered from regulated 24 V rails. Both share identical DO-214AC packaging and mounting.
SMAJ20A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 12.3A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ20A FAQ
1.How can I place an order for SMAJ20A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ20A 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 SMAJ20A reliable?
The price and inventory of SMAJ20A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ20A is usually 5 days.
3.What payment methods are accepted for SMAJ20A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ20A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ20A?
SMAJ20A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ20A 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 SMAJ20A?
For technical support, including SMAJ20A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ20A requirements.
6.How does Aetrix verify that SMAJ20A is sourced from the original manufacturer or authorized distributors?
All SMAJ20A 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 SMAJ20A meets industry standards.
7.What is the process for return or replacement of SMAJ20A?
All SMAJ20A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ20A, 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 SMAJ20A part is unused and in its original packaging.
Return procedure for SMAJ20A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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