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Taiwan Semiconductor Corporation SMAJ20
- Part No.:
- SMAJ20
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ20.pdf
- Description:
- 400W, 24.7V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:6,294
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Product details
Overview
SMAJ20 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 20 V working stand-off voltage (VWM), 22.2–27.1 V breakdown voltage (VBR) at 1 mA test current, 35.8 V maximum clamping voltage (VC) under 11.2 A peak impulse current, and 400 W peak pulse power rating with 10/1000 µs waveform - ideal for protecting SMPS inputs and automotive load-dump-sensitive circuits.
For engineers reviewing the SMAJ20 datasheet, SMAJ20 pinout, SMAJ20 application, or SMAJ20 equivalent, key selection criteria include its DO-214AC (SMA) package compatibility, bidirectional variant availability (SMAJ20A), ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, and precise clamping performance at rated surge current - critical for industrial power adapter and on-board DC/DC converter designs.
Technical Context
The SMAJ20 operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology to achieve sub-1 ps response time and low leakage (<1 µA at 20 V). Its clamping behavior is defined by a tightly controlled VBR range (22.2–27.1 V) and guaranteed VC ≤35.8 V at IPPM = 11.2 A, enabling predictable protection margin above system operating voltage.
Thermally rated for TJ = –55°C to +150°C and packaged in DO-214AC (SMA), the device supports automated placement and meets JESD201 Class 2 whisker resistance, UL 94V-0 molding compound, and RoHS/halogen-free requirements - aligning with high-reliability industrial and automotive PCB assembly standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 20 V - Maximum continuous reverse voltage before significant leakage; sets upper limit for protected circuit operating voltage. |
| VBR min/max | 22.2 V / 27.1 V at IT = 1 mA - Confirmed avalanche onset range; ensures reliable triggering above VWM with margin. |
| VC @ IPPM | 35.8 V at 11.2 A (10/1000 µs) - Clamped voltage during worst-case surge; defines peak stress on downstream components. |
| PPPM | 400 W - Peak pulse power handling per standard waveform; validates suitability for IEC 61000-4-5 Level 4 surges. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage at operating voltage; minimizes standby power loss in battery-backed systems. |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline; enables high-density layout and reflow compatibility. |
Pinout & Package
DO-214AC (SMA) package: cathode-banded end denotes terminal 1 (cathode); anode is terminal 2. Molded epoxy case with matte tin-plated leads; polarity marked by single black band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Protected line connection point | Connected to rail requiring overvoltage clamping; reverse-biased during normal operation. |
| Anode | Reference/ground return path | Tied to system ground or lower-potential reference; completes clamping current path during transients. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Enables stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure. |
| <1 ps response time | Clamps ESD and fast transients before sensitive ICs experience overstress - critical for USB, CAN, and sensor interfaces. |
| ISO 7637-2 compliance | Validated for automotive Pulse 1 (inductive switch-off), Pulse 2a/2b (load dump), and Pulse 3a/3b (capacitive coupling) waveforms. |
| Moisture sensitivity level 1 | Zero bake requirement prior to reflow; supports standard SMT assembly without moisture-related popcorning risk. |
Applications
| Switching Mode Power Supply (SMPS) | Automotive On-Board DC/DC Converter |
|---|---|
Use Scenario: Input stage of 24 V industrial SMPS subjected to line surges and lightning-induced transients. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed across input bulk capacitor to clamp positive-going overvoltages. Use Value: Limits transient voltage to ≤35.8 V, protecting primary-side controller and MOSFET gate drivers from breakdown. |
Use Scenario: 12 V to 3.3 V buck converter in automotive body control module exposed to load-dump events. IC Role / Device Role / Timing Role: Primary overvoltage clamp on converter input rail, activated within <1 ps of surge onset. Use Value: Withstands 400 W peak pulse energy per ISO 7637-2 Pulse 2b, preventing regulator latch-up or destruction. |
| LED Driver Power Adapter | Industrial PLC Digital Input Module |
Use Scenario: Constant-current LED driver powered from 24 V AC/DC adapter in outdoor lighting. IC Role / Device Role / Timing Role: Standoff-rated TVS on adapter output to suppress switching noise and induced surges. Use Value: 20 V VWM matches nominal output; 35.8 V VC ensures LED string and driver IC remain below absolute max ratings. |
Use Scenario: 24 V digital input channel in programmable logic controller interfacing with field sensors. IC Role / Device Role / Timing Role: Front-end transient protector on input terminal block, shunting surge current to chassis ground. Use Value: Sub-1 µA IR prevents false triggering in high-impedance sensing circuits; DO-214AC footprint fits compact I/O module layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20A | Bidirectional variant; symmetric VBR (22.2–24.5 V) and higher clamping (32.4 V) at same IPPM; identical VWM. | Required for AC-coupled or dual-polarity signal lines (e.g., RS-485, CAN bus); not suitable for DC rail-only protection. | Select SMAJ20A only when bidirectional clamping is mandated by signal topology or standard compliance. |
| SMBJ20 | Same VWM/VBR/VC specs but in DO-214AA (SMB) package; 600 W PPPM rating (vs. 400 W); higher IFSM (100 A vs. 40 A). | Better suited for higher-energy surges (e.g., IEC 61000-4-5 Level 5); larger footprint may limit high-density designs. | Choose SMBJ20 when surge energy exceeds 400 W capability or when enhanced forward surge robustness is required. |
Compared with SMAJ20A, the SMAJ20 offers superior unidirectional clamping efficiency for DC rails, while SMBJ20 provides higher pulse power headroom at the cost of board space - making SMAJ20 the optimal balance of size, cost, and 400 W surge protection for space-constrained 24 V industrial systems.
Availability
SMAJ20 is available at Aetrix Electronics and suitable for switching mode power supplies, automotive DC/DC converters, and LED lighting adapters requiring stable component supply and full traceability through production lifecycles.
Supply support for SMAJ20 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 industrial and automotive markets.
The SMAJ series was developed specifically for high-reliability, surface-mount transient suppression in harsh environments - emphasizing low clamping voltage, fast response, and AEC-Q200-aligned robustness.
FAQ
What is the maximum clamping voltage of SMAJ20 under standard surge conditions?
The SMAJ20 has a maximum clamping voltage (VC) of 35.8 V when subjected to a 10/1000 µs waveform peak impulse current of 11.2 A. This value is measured per JEDEC standards and guarantees that downstream components see no more than 35.8 V during a 400 W transient event - a critical parameter for ensuring safe operation of 24 V-rated ICs and MOSFETs in the protected circuit.
Is SMAJ20 suitable for automotive applications compliant with ISO 7637-2?
Yes, SMAJ20 meets ISO 7637-2 requirements for Pulse 1 (inductive switch-off), Pulse 2a/2b (load dump), and Pulse 3a/3b (capacitive coupling), as confirmed in Taiwan Semiconductor's official documentation. Its 400 W peak pulse power rating, 150 °C junction temperature limit, and DO-214AC packaging make it appropriate for use in automotive body electronics, infotainment power supplies, and ADAS sensor modules where transient immunity is mandatory.
How does SMAJ20 differ from SMAJ20A in terms of electrical behavior?
SMAJ20 is unidirectional, with clamping action only for positive transients relative to ground, whereas SMAJ20A is bidirectional and clamps both polarities symmetrically. SMAJ20A exhibits a lower maximum clamping voltage (32.4 V vs. 35.8 V) but shares identical VWM (20 V) and VBR range (22.2–24.5 V). The choice depends strictly on signal topology: SMAJ20 for DC rails, SMAJ20A for AC or differential lines like CAN or RS-485.
What is the reverse leakage current specification for SMAJ20 at its working voltage?
The SMAJ20 specifies a maximum reverse leakage current (IR) of 1 µA when biased at its full working stand-off voltage (VWM) of 20 V. This ultra-low leakage ensures minimal power loss in always-on systems such as battery-powered sensors or standby circuits, and supports high-impedance monitoring nodes without introducing measurement error or premature discharge.
Does SMAJ20 require special handling or baking before reflow soldering?
No, SMAJ20 is rated at Moisture Sensitivity Level (MSL) 1 per J-STD-020, meaning it has unlimited floor life and requires no pre-reflow baking. Its DO-214AC (SMA) package uses moisture-resistant epoxy and matte tin-plated leads compatible with standard Pb-free reflow profiles - simplifying manufacturing and reducing process risk in high-volume SMT lines.
SMAJ20 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:
- 35.8V
- Current - Peak Pulse (10/1000µs):
- 11.2A
- 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)
SMAJ20 FAQ
1.How can I place an order for SMAJ20 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ20 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 SMAJ20 reliable?
The price and inventory of SMAJ20 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ20 is usually 5 days.
3.What payment methods are accepted for SMAJ20?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ20 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ20?
SMAJ20 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ20 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 SMAJ20?
For technical support, including SMAJ20 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ20 requirements.
6.How does Aetrix verify that SMAJ20 is sourced from the original manufacturer or authorized distributors?
All SMAJ20 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 SMAJ20 meets industry standards.
7.What is the process for return or replacement of SMAJ20?
All SMAJ20 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ20, 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 SMAJ20 part is unused and in its original packaging.
Return procedure for SMAJ20:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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