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Taiwan Semiconductor Corporation SMAJ120CH
- Part No.:
- SMAJ120CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ120CH.pdf
- Description:
- TVS DIODE 120VWM 214VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,923
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Product details
Overview
SMAJ120CH from Taiwan Semiconductor is a unidirectional 400W transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for automotive-grade overvoltage protection with 120V working stand-off voltage, 133–163V breakdown voltage at 1mA test current, and 214V maximum clamping voltage at 1.4A peak impulse current under 10/1000μs waveform. It is AEC-Q101 qualified and used in on-board DC/DC converters to protect sensitive power electronics from ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMAJ120CH datasheet, SMAJ120CH pinout, SMAJ120CH application, or SMAJ120CH equivalent, key selection criteria include clamping voltage margin relative to system rail, unidirectional polarity marking, DO-214AC thermal derating above 25°C, and compliance with automotive surge immunity standards-especially where fast response (<1ps), low leakage (<1μA at 120V), and moisture sensitivity level 1 handling are required.
Technical Context
The SMAJ120CH operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its 133–163V breakdown range. Its glass-passivated junction ensures stable VBR tolerance and low leakage, while the DO-214AC package provides 1W steady-state dissipation and supports automated placement per J-STD-002 solderability requirements.
It delivers 400W peak pulse power (10/1000μs) up to 25°C, derated linearly above that ambient temperature per Fig.2, and meets ISO 7637-2 Pulse 1 (inductive load dump suppression), Pulse 2a/2b (battery disconnect/relay bounce), and Pulse 3a/3b (capacitive coupling transients). Polarity is marked by cathode band on the package body.
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 circuit rail |
| VBR min/max | 133 V / 163 V @ 1 mA - Breakdown voltage range defining turn-on threshold; tight tolerance enables predictable clamping onset |
| VC @ IPPM | 214 V @ 1.4 A - Clamping voltage during 10/1000μs surge; determines worst-case overvoltage seen by downstream ICs |
| PPPM | 400 W @ 10/1000μs - Peak surge energy absorption capacity; sufficient for ISO 7637-2 Pulse 1 at 12V systems |
| IR @ VWM | <1 μA - Reverse leakage at rated stand-off voltage; negligible power loss and no thermal runaway risk |
| TJ max | +150 °C - Maximum junction temperature; supports under-hood automotive environments with proper PCB copper area |
| Package | DO-214AC (SMA) - 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 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.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path); conducts during forward surge or ESD events |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 12V rail); avalanches into conduction when reverse voltage exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood use including temperature cycling, humidity bias, and mechanical shock testing |
| Glass passivated junction | Ensures stable VBR over time and temperature, with <1μA IR at 120V and minimal parameter drift across life |
| Fast response time | <1.0 ps from 0 V to VBR min - faster than most microcontroller I/O protection needs, enabling sub-nanosecond transient capture |
| ISO 7637-2 compliance | Meets Pulse 1 (load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (line capacitance coupling) without external filtering |
| Moisture sensitivity level 1 | No floor-life limitation or bake requirement prior to reflow; compatible with standard SMT assembly lines |
Applications
| Switching Mode Power Supply (SMPS) | On-board DC/DC Converter |
|---|---|
Use Scenario: Protecting primary-side MOSFET gate drivers and secondary-side synchronous rectifiers from flyback spikes and cross-conduction surges. IC Role / Device Role / Timing Role: Unidirectional TVS placed across input/output rails to clamp transient overvoltages before they reach controller ICs or power stages. Use Value: Limits peak rail excursions to ≤214V during 400W 10/1000μs surges, preserving MOSFET VDS rating margin and preventing latch-up in PWM controllers. | Use Scenario: Safeguarding 12V-to-3.3V buck converter inputs in automotive infotainment modules exposed to battery line transients. IC Role / Device Role / Timing Role: Standoff protection device mounted directly at DC/DC input terminals to absorb ISO 7637-2 Pulse 1 energy before it propagates to regulator ICs. Use Value: Withstands 1.4A peak impulse at 120V stand-off, ensuring output regulation remains stable even during 100V load-dump events on vehicle battery lines. |
| Lighting Application | Adapters |
Use Scenario: Shielding LED driver ICs in headlamp modules from ignition noise and alternator ripple-induced voltage spikes. IC Role / Device Role / Timing Role: Bidirectional-capable variant not required; unidirectional SMAJ120CH clamps negative-going transients on grounded return paths. Use Value: 214V clamping voltage maintains >10V margin below typical 24V LED string supply rails, preventing premature driver shutdown or overvoltage fault triggering. | Use Scenario: Suppressing ESD and line surges in universal AC/DC wall adapters used in industrial control panels. IC Role / Device Role / Timing Role: Input-stage transient suppressor placed after bridge rectifier but before bulk capacitor to reduce stress on smoothing capacitors and primary-side controllers. Use Value: 400W peak power rating handles repetitive 10/1000μs surges common in factory floor environments, extending adapter lifetime beyond 50,000 cycles. |
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 | Breakdown range 133–147V (tighter VBR tolerance), same DO-214AC package and 214V VC | Lower VBR max reduces clamping uncertainty in high-temperature operation but may increase leakage slightly above 120V | Select when tighter VBR distribution improves design margin for 12V nominal systems with wide temperature range |
| Vishay SMAJ120AHE3/5A | AEC-Q101 qualified, same electrical specs, halogen-free per IEC 61249-2-21, RoHS-compliant | Identical performance envelope; differs only in tape-and-reel packaging and traceability documentation | Choose for dual-sourcing or when Vishay's logistics and traceability protocols align with OEM procurement requirements |
Compared with SMAJ120CH, SMAJ120A offers narrower VBR spread for improved consistency in production lots, while SMAJ120AHE3/5A provides identical protection performance with alternate supply-chain validation-neither is pin-compatible by default, but all three share DO-214AC footprint and unidirectional polarity marking.
Availability
SMAJ120CH is available at Aetrix Electronics and suitable for automotive power management, industrial DC/DC conversion, and lighting control applications requiring stable component supply, AEC-Q101 compliance, and ISO 7637-2 surge immunity.
Supply support for SMAJ120CH 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 automotive-qualified power devices.
The SMAJ series was developed specifically for automotive and industrial transient suppression, emphasizing AEC-Q101 reliability, fast clamping response, and compatibility with high-volume SMT assembly processes.
FAQ
What is the polarity configuration of the SMAJ120CH?
The SMAJ120CH is a unidirectional TVS diode with cathode indicated by a band on the DO-214AC package body. When installed, the cathode connects to the protected line (e.g., 12V rail), and the anode connects to ground or the lower-potential reference. This configuration allows it to clamp only reverse-voltage transients while remaining non-conductive during normal forward-biased operation. The SMAJ120CH does not conduct in the forward direction except during surge events exceeding its 3.5V forward voltage at 25A.
Does the SMAJ120CH meet automotive qualification standards?
Yes, the SMAJ120CH is AEC-Q101 qualified, meaning it has passed stress tests including high-temperature operating life, temperature cycling, humidity bias, and mechanical shock specific to discrete semiconductors used in automotive applications. It also meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b immunity requirements, making it suitable for under-hood and body-control module deployments where robustness against battery line transients is mandatory. The SMAJ120CH data sheet confirms full compliance with these standards.
What is the maximum clamping voltage of the SMAJ120CH under surge conditions?
The SMAJ120CH has a maximum clamping voltage (VC) of 214 V at 1.4 A peak impulse current under the standardized 10/1000μs double-exponential waveform. This value represents the highest voltage the device will allow across its terminals during a 400W transient event at 25°C ambient. At elevated temperatures, VC increases slightly due to positive temperature coefficient of avalanche voltage, but remains within safe margins for 12V and 24V automotive systems. The SMAJ120CH datasheet specifies this parameter in the Electrical Specifications table on page 3.
Can the SMAJ120CH be used in bidirectional applications?
No, the SMAJ120CH is strictly unidirectional and must not be used for bidirectional surge suppression. For bidirectional protection, Taiwan Semiconductor offers the SMAJ120AH variant (marked SG), which features symmetrical breakdown in both directions. Using the SMAJ120CH in reverse-biased configurations without proper polarity alignment will result in immediate failure. Always verify marking code "SF" (SMAJ120CH) versus "SG" (SMAJ120AH) before placement. The SMAJ120CH datasheet explicitly states that electrical characteristics apply only in the reverse direction for unidirectional types.
What is the thermal derating behavior of the SMAJ120CH above 25°C?
The SMAJ120CH exhibits linear thermal derating of peak pulse power above 25°C ambient, as defined in Fig.2 of the datasheet: at 75°C, its 400W rating drops to approximately 250W; at 125°C, it falls to ~120W. This derating applies to both single-pulse and repetitive surge conditions. Steady-state power dissipation remains fixed at 1W regardless of temperature. PCB layout-particularly copper area connected to both leads-directly impacts effective junction temperature; the SMAJ120CH requires minimum 25 mm² of 1oz copper per lead for full-rated performance at elevated ambient.
SMAJ120CH 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:
- -
- Bidirectional Channels:
- 1
- 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ120CH FAQ
1.How can I place an order for SMAJ120CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ120CH 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 SMAJ120CH reliable?
The price and inventory of SMAJ120CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ120CH is usually 5 days.
3.What payment methods are accepted for SMAJ120CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ120CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ120CH?
SMAJ120CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ120CH 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 SMAJ120CH?
For technical support, including SMAJ120CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ120CH requirements.
6.How does Aetrix verify that SMAJ120CH is sourced from the original manufacturer or authorized distributors?
All SMAJ120CH 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 SMAJ120CH meets industry standards.
7.What is the process for return or replacement of SMAJ120CH?
All SMAJ120CH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ120CH, 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 SMAJ120CH part is unused and in its original packaging.
Return procedure for SMAJ120CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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