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Taiwan Semiconductor Corporation SMAJ120A
- Part No.:
- SMAJ120A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ120A.pdf
- Description:
- TVS DIODE 120VWM 193VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,653
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Product details
Overview
SMAJ120A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for primary-side overvoltage protection in DC power rails. It features a 120 V working stand-off voltage (VWM), 133–147 V breakdown voltage (VBR), 193 V maximum clamping voltage (VC) at 1.6 A peak impulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - suitable for automotive load-dump and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance.
For engineers reviewing the SMAJ120A datasheet, SMAJ120A pinout, SMAJ120A application, or SMAJ120A equivalent, this device is selected for high-reliability DC/DC converter input protection, SMPS secondary-side surge suppression, and industrial adapter line-transient immunity where fast clamping (<1 ps response), low leakage (<1 µA @ 120 V), and DO-214AC package compatibility are critical.
Technical Context
The SMAJ120A operates as a unidirectional avalanche diode with glass-passivated junction, enabling stable breakdown behavior under repetitive transients. Its clamping action begins at VBR = 133–147 V (tested at 1 mA), limiting induced surges to ≤193 V at IPPM = 1.6 A - verified per 10/1000 µs waveform per REA standard.
Thermal performance is defined by TJMAX = 150 °C and steady-state power dissipation of 1 W, with derating above 25 °C per Fig.2. It meets JESD201 Class 2 whisker resistance and J-STD-020 Moisture Sensitivity Level 1, supporting lead-free reflow without preconditioning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 120 V - Maximum continuous reverse operating voltage before leakage exceeds 1 µA; sets upper limit for protected rail voltage. |
| VBR min/max | 133 V / 147 V @ 1 mA - Confirmed avalanche onset range; ensures predictable turn-on margin above VWM. |
| VC @ IPPM | 193 V @ 1.6 A - Clamped voltage during 10/1000 µs surge; defines worst-case stress on downstream components. |
| PPPM | 400 W - Peak pulse power handling per standard waveform; supports single-event automotive load dump (ISO 7637-2 Pulse 5a). |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off; enables low-power standby operation without system drain. |
| TJMAX | 150 °C - Maximum junction temperature; allows operation in under-hood or enclosed industrial enclosures. |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline with 0.060 g mass, UL 94V-0 molding, and matte tin-plated leads. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with cathode band marking; anode and cathode terminals aligned for automated placement on PCBs. Matte tin-plated leads meet J-STD-002 solderability requirements and JESD201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current sink during reverse-biased clamping | Connected to protected circuit ground or low-side return path; carries full surge current during transient event. |
| Cathode | High-impedance input during normal operation; clamps to VC during overvoltage | Connected to protected line (e.g., +12 V rail); polarity mark (band) must align with schematic symbol to prevent misapplication. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure. |
| Sub-1 ps response time | Enables clamping before sensitive ICs (e.g., MCU power pins or gate drivers) experience damaging overvoltage. |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect), and Pulse 3a/3b (line spikes) - no additional filtering required. |
| Halogen-free & RoHS-compliant | Meets IEC 61249-2-21 and EU Directive 2011/65/EU; supports green manufacturing and end-of-life recycling. |
| MSL Level 1 | Zero floor life limitation - can be stored indefinitely at ≤30 °C/60% RH and placed directly into reflow without baking. |
Applications
| Automotive Power Distribution | Industrial DC/DC Converters |
|---|---|
Use Scenario: Protecting 12 V battery-fed control modules against load-dump transients up to 35 V for 400 ms. IC Role / Device Role / Timing Role: Primary-line TVS clamp placed upstream of DC/DC controller ICs and LDO regulators. Use Value: Limits voltage to ≤193 V during ISO 7637-2 Pulse 5a events, preventing latch-up or oxide rupture in 3.3 V/5 V logic supplies. |
Use Scenario: Safeguarding isolated 24 V to 5 V flyback converter inputs from switching noise and ESD coupling. IC Role / Device Role / Timing Role: Input-rail transient suppressor positioned between connector and primary-side MOSFET gate driver. Use Value: Absorbs 400 W surges without degradation, maintaining <1 µA leakage to preserve no-load efficiency in energy-sensitive designs. |
| LED Driver Power Stages | Telecom Power Feeds |
Use Scenario: Securing constant-current LED driver inputs against lightning-induced surges on outdoor signage power lines. IC Role / Device Role / Timing Role: Unidirectional surge protector on AC/DC rectified output bus prior to buck controller. Use Value: Clamps 10/1000 µs transients to 193 V within 1 ps, avoiding false triggering of overvoltage protection in PWM dimming circuits. |
Use Scenario: Hardening -48 V telecom power feed inputs against accidental short-to-battery or hot-swap spikes. IC Role / Device Role / Timing Role: Standoff-rated TVS on central office power distribution board feeding remote PHY modules. Use Value: Withstands 1.6 A peak impulse at 120 V nominal, meeting Telcordia GR-1089-CORE Level 3 surge immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ120 | Bidirectional variant; symmetric VBR = 133–163 V; higher VC = 214 V @ 1.4 A. | Required only when bidirectional surge protection (e.g., AC-coupled signal lines) is needed; not suitable for unidirectional DC rails. | Select SMAJ120A for DC power rail protection where polarity is fixed and lower clamping voltage is critical. |
| SMBJ120A | Same VWM/VBR/VC specs but in DO-214AA (SMB) package; 600 W PPPM, higher IPPM = 2.7 A. | Used where higher surge margin is required (e.g., front-end power entry) and PCB space allows larger SMB footprint. | Choose SMBJ120A if system-level testing shows 400 W insufficient; SMAJ120A remains optimal for space-constrained board layouts. |
Compared with SMAJ120 and SMBJ120A, the SMAJ120A delivers the lowest clamping voltage (193 V) in the smallest DO-214AC footprint - making it ideal for compact, unidirectional DC protection where layout area and voltage margin are tightly constrained.
Availability
SMAJ120A is available at Aetrix Electronics and suitable for automotive power distribution, industrial DC/DC converters, and LED driver power stages requiring stable component supply across extended production cycles.
Supply support for SMAJ120A 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and power MOSFETs since 1979.
The SMAJ series was developed for high-reliability, surface-mount transient suppression in automotive and industrial power systems - emphasizing low clamping, fast response, and robust packaging for automated assembly.
FAQ
What is the maximum clamping voltage of the SMAJ120A under standard test conditions?
The SMAJ120A has a maximum clamping voltage (VC) of 193 V when subjected to a 10/1000 µs waveform at IPPM = 1.6 A. This value is measured per REA-defined pulse shape and represents the peak voltage seen by downstream components during a standardized surge event. The SMAJ120A maintains this clamping performance across its full operating temperature range (-55 °C to +150 °C), ensuring consistent protection in harsh environments.
Is the SMAJ120A suitable for bidirectional signal line protection?
No, the SMAJ120A is a unidirectional TVS diode intended exclusively for DC power rail protection. Its cathode-band marking and asymmetric IV curve mean it conducts only during reverse overvoltage events. For bidirectional applications such as data lines or AC-coupled interfaces, the SMAJ120 (bidirectional variant) or SMAJ120CA should be used instead. Using SMAJ120A on bidirectional paths risks forward conduction failure or inadequate clamping in one polarity.
How does the SMAJ120A compare to the SMAJ120 in terms of leakage current and clamping performance?
The SMAJ120A exhibits lower maximum clamping voltage (193 V vs. 214 V) and tighter VBR tolerance (133–147 V vs. 133–163 V), resulting in more precise and lower-voltage surge suppression. Both share identical VWM = 120 V and IR < 1 µA @ VWM. However, the SMAJ120A's optimized unidirectional structure reduces dynamic impedance, making it preferable for DC power rails where minimal voltage overshoot is critical - unlike the SMAJ120, which sacrifices clamping performance for bidirectional symmetry.
Does the SMAJ120A require moisture preconditioning before reflow soldering?
No, the SMAJ120A is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life at ≤30 °C/60% RH and may be placed directly into reflow without baking or dry-pack storage. Its DO-214AC (SMA) package uses moisture-resistant epoxy molding compound, eliminating moisture-induced popcorning risk during lead-free reflow profiles - simplifying manufacturing logistics and reducing process overhead for high-volume SMT lines.
Can the SMAJ120A be used in place of the SMBJ120A for space-constrained designs?
Yes, the SMAJ120A is a direct functional alternative to the SMBJ120A in applications where 400 W peak pulse power suffices and PCB real estate is limited. While the SMBJ120A offers higher 600 W rating and 2.7 A IPPM in the larger DO-214AA (SMB) package, the SMAJ120A delivers identical VWM, VBR, and VC specs in the smaller DO-214AC footprint - enabling drop-in replacement where surge energy is within 400 W limits and layout density is prioritized.
SMAJ120A 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):
- 120V
- Voltage - Breakdown (Min):
- 133V
- Voltage - Clamping (Max) @ Ipp:
- 193V
- Current - Peak Pulse (10/1000µs):
- 1.6A
- 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)
SMAJ120A FAQ
1.How can I place an order for SMAJ120A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ120A 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 SMAJ120A reliable?
The price and inventory of SMAJ120A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ120A is usually 5 days.
3.What payment methods are accepted for SMAJ120A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ120A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ120A?
SMAJ120A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ120A 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 SMAJ120A?
For technical support, including SMAJ120A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ120A requirements.
6.How does Aetrix verify that SMAJ120A is sourced from the original manufacturer or authorized distributors?
All SMAJ120A 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 SMAJ120A meets industry standards.
7.What is the process for return or replacement of SMAJ120A?
All SMAJ120A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ120A, 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 SMAJ120A part is unused and in its original packaging.
Return procedure for SMAJ120A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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