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Taiwan Semiconductor Corporation SMAJ120
- Part No.:
- SMAJ120
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ120.pdf
- Description:
- 300W, 148V, 10%, UNIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:2,567
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Product details
Overview
SMAJ120 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 120 V working stand-off voltage (VWM), 133–163 V breakdown voltage (VBR @ 1 mA), 214 V maximum clamping voltage (VC) at 1.4 A peak impulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - suitable for automotive load-dump and industrial surge immunity.
For engineers reviewing the SMAJ120 datasheet, SMAJ120 pinout, SMAJ120 application, or SMAJ120 equivalent, this page delivers verified electrical parameters, DO-214AC package dimensions, clamping behavior under ISO 7637-2 Pulse 1/2a/2b/3a/3b, junction temperature limits, and real-world alternative part comparisons - all critical for ESD/surge protection design validation and BOM selection.
Technical Context
The SMAJ120 operates as a unidirectional avalanche diode with glass-passivated junction, enabling sub-1 ps response to transients and <1 µA reverse leakage above VWM. Its clamping action begins at VBR = 133–163 V and sustains up to 214 V at IPPM = 1.4 A, delivering precise overvoltage limiting without forward conduction during normal operation.
Rated for TJ = –55°C to +150°C and housed in DO-214AC (SMA) package, it meets J-STD-020 moisture sensitivity level 1 and UL 94V-0 flammability. It complies with ISO 7637-2 for automotive electronics but is not bidirectional - no "CA" suffix, and polarity is marked by cathode band.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 120 V - Maximum continuous DC or RMS voltage the device blocks without clamping; defines safe operating margin before breakdown. |
| VBR @ IT = 1 mA | 133–163 V - Measured breakdown range confirming avalanche onset threshold; ensures predictable turn-on under surge conditions. |
| VC @ IPPM = 1.4 A | 214 V - Clamped voltage during 10/1000 µs transient; determines maximum stress imposed on downstream circuitry. |
| PPPM | 400 W - Peak pulse power handling capability; validates survivability against standardized surge waveforms including ISO 7637-2. |
| IR @ VWM | <1 µA - Reverse leakage current at rated stand-off voltage; ensures minimal standby power loss and signal integrity in high-impedance nodes. |
| TJ max | +150 °C - Maximum junction temperature; supports operation in under-hood automotive or enclosed industrial environments. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with matte tin-plated leads; compatible with automated reflow assembly per J-STD-002. |
Pinout & Package
DO-214AC (SMA) package: molded epoxy case with axial lead configuration, cathode indicated by a band on one end. Leads are matte tin-plated, solderable per J-STD-002, and meet JESD 201 Class 2 whisker resistance. Weight ≈ 0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input/line side (non-banded end) | Connected to protected line; conducts only during reverse-biased avalanche - must be placed upstream of sensitive ICs. |
| Cathode | Ground/reference side (banded end) | Connected to system ground or low-impedance return path; establishes clamping reference and defines unidirectional polarity. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable, repeatable avalanche characteristics across temperature and lifetime; eliminates surface degradation risks in humid environments. |
| Sub-1 ps response time | Enables suppression of fast-rising ESD and lightning-induced transients before they propagate into IC inputs or power converters. |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Validates suitability for 12 V automotive ECUs, infotainment systems, and body control modules subject to battery-line disturbances. |
| Moisture sensitivity level 1 (J-STD-020) | Permits unlimited floor life before reflow; eliminates baking requirements and simplifies SMT manufacturing logistics. |
| RoHS & halogen-free (IEC 61249-2-21) | Meets global environmental compliance mandates for industrial, medical, and consumer electronics without sacrificing surge performance. |
Applications
| Automotive Body Control Module (BCM) | Industrial DC/DC Converter Input Stage |
|---|---|
Use Scenario: Protects microcontroller I/O and CAN transceiver power rails from load-dump spikes (up to 35 V) and jump-start surges in 12 V vehicle systems. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery feed and local regulator input; clamps transients within 1 ps to limit voltage seen by LDOs and MCUs. Use Value: Maintains VC ≤ 214 V during 400 W pulses, preventing latch-up or gate oxide damage in downstream silicon while supporting ISO 7637-2 Pulse 5a compliance. |
Use Scenario: Shields isolated flyback or buck converter primary-side MOSFET gate drivers and feedback optocouplers from reflected surge energy on 24–48 V industrial bus inputs. IC Role / Device Role / Timing Role: Standoff-rated TVS mounted directly at board edge connector; absorbs 10/1000 µs transients before they couple into transformer windings or control ICs. Use Value: Delivers 400 W pulse handling with <1 µA leakage at 120 V, minimizing standby loss while ensuring >150 °C thermal survival in sealed enclosures. |
| LED Streetlight Power Supply | Telecom Remote Radio Unit (RRU) DC Feed |
Use Scenario: Guards AC/DC PFC stage and constant-current LED driver ICs against lightning-induced surges on outdoor-rated 230 VAC input lines. IC Role / Device Role / Timing Role: Secondary-side TVS on bulk capacitor rail; clamps residual transients that pass through MOV-based front-end filtering. Use Value: With VWM = 120 V and VC = 214 V, it provides 1.78× overvoltage margin relative to 120 V nominal DC bus, enabling reliable operation in high-surge zones. |
Use Scenario: Protects PoE-powered remote radio units fed via long outdoor copper runs exposed to induced surges from nearby lightning strikes. IC Role / Device Role / Timing Role: DC-input TVS on -48 V telecom supply rail; placed upstream of DC/DC isolation stage to prevent common-mode surge propagation. Use Value: 214 V clamping ceiling ensures downstream SiC MOSFETs and gate drivers remain below absolute maximum ratings even during worst-case 10/1000 µs events. |
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 SMAJ120A | Lower VBR range (133–147 V) and lower VC (193 V @ 1.6 A); same DO-214AC package and 400 W rating. | Better clamping ratio (193/120 = 1.61 vs. SMAJ120's 214/120 = 1.78), advantageous where downstream voltage margin is tight. | Select SMAJ120A when lower clamping voltage is prioritized over higher VBR tolerance; verify layout compatibility with identical footprint. |
| Vishay SMAJ120 | Identical VWM, VBR, VC, and PPPM; minor differences in IR (<1 µA vs. <0.5 µA) and moisture sensitivity (MSL 1 vs. MSL 1). | No functional deviation; validated for same ISO 7637-2 pulses and automotive temperature profile. | Drop-in alternative with full parametric equivalence; preferred where Vishay supply chain alignment or dual-sourcing is required. |
Compared with SMAJ120, the SMAJ120A offers tighter clamping at the cost of reduced VBR tolerance, while Vishay's SMAJ120 matches all key specs exactly - making it a true functional replacement for continuity-critical designs.
Availability
SMAJ120 is available at Aetrix Electronics and suitable for automotive body control modules, industrial DC/DC converters, and LED streetlight power supplies requiring stable component supply, long-term lifecycle support, and traceable RoHS-compliant sourcing.
Supply support for SMAJ120 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, serving global automotive, industrial, and consumer markets since 1979.
The SMAJ series is part of TSC's transient voltage suppressor product line, engineered specifically for high-reliability surge immunity in harsh environments - emphasizing fast response, stable clamping, and automotive-grade qualification.
FAQ
What is the maximum clamping voltage of the SMAJ120 under standard test conditions?
The SMAJ120 exhibits a maximum clamping voltage (VC) of 214 V when subjected to a 10/1000 µs peak impulse current of 1.4 A. This value is measured per JEDEC standards and represents the upper voltage limit imposed on protected circuitry during surge events - a critical parameter for ensuring downstream ICs remain within their absolute maximum ratings. The SMAJ120 maintains this clamping performance across its full operating temperature range.
Is the SMAJ120 suitable for bidirectional transient suppression?
No, the SMAJ120 is a unidirectional TVS diode, as confirmed by its single cathode band marking and absence of "CA" suffix. It conducts only in reverse bias during overvoltage events and must be oriented with cathode toward ground. For bidirectional protection, the SMAJ120A variant is not applicable - instead, use SMAJ120CA or equivalent symmetrical devices. The SMAJ120 datasheet explicitly states electrical characteristics apply in one direction only.
What package type does the SMAJ120 use, and is it compatible with standard SMT processes?
The SMAJ120 uses the DO-214AC (SMA) surface-mount package, featuring matte tin-plated leads qualified per J-STD-002 for solderability and JESD 201 Class 2 for whisker resistance. Its moisture sensitivity level is J-STD-020 Level 1, allowing unlimited floor life before reflow. The SMAJ120 is fully compatible with standard infrared and vapor-phase reflow profiles used for automotive and industrial PCB assembly.
How does the SMAJ120 perform under ISO 7637-2 automotive transient testing?
The SMAJ120 is explicitly rated to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b waveforms - covering typical automotive electrical disturbances such as inductive load dump, supply interruption, and capacitive coupling. Its 400 W peak pulse power rating and 214 V clamping voltage ensure compliance when correctly applied on 12 V systems with appropriate PCB layout and grounding. The SMAJ120's glass-passivated junction contributes to consistent performance across repeated surge events.
What is the operating junction temperature range for the SMAJ120?
The SMAJ120 is rated for an operating junction temperature range of –55°C to +150°C, as specified in its Absolute Maximum Ratings table. This wide thermal envelope supports deployment in under-hood automotive locations, industrial motor drives, and outdoor lighting systems. Derating of peak pulse power begins above 25°C ambient per the published pulse derating curve (Fig.2), and the device's DO-214AC package enables effective thermal dissipation in properly designed layouts.
SMAJ120 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:
- 214V
- Current - Peak Pulse (10/1000µs):
- 1.4A
- 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)
SMAJ120 FAQ
1.How can I place an order for SMAJ120 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ120 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 SMAJ120 reliable?
The price and inventory of SMAJ120 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ120 is usually 5 days.
3.What payment methods are accepted for SMAJ120?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ120 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ120?
SMAJ120 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ120 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 SMAJ120?
For technical support, including SMAJ120 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ120 requirements.
6.How does Aetrix verify that SMAJ120 is sourced from the original manufacturer or authorized distributors?
All SMAJ120 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 SMAJ120 meets industry standards.
7.What is the process for return or replacement of SMAJ120?
All SMAJ120 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ120, 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 SMAJ120 part is unused and in its original packaging.
Return procedure for SMAJ120:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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