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Taiwan Semiconductor Corporation SMAJ40CH
- Part No.:
- SMAJ40CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ40CH.pdf
- Description:
- TVS DIODE 40VWM 71.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,100
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Product details
Overview
SMAJ40CH from Taiwan Semiconductor is a unidirectional 400W transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for automotive-grade overvoltage protection with 40 V working stand-off voltage, 44.4–54.3 V breakdown voltage at 1 mA test current, and 71.4 V maximum clamping voltage at 5.6 A peak impulse current under 10/1000 µs waveform - deployed in on-board DC/DC converters to safeguard power rails against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMAJ40CH datasheet, SMAJ40CH pinout, SMAJ40CH application, or SMAJ40CH equivalent, this page delivers verified electrical parameters, AEC-Q101 qualification status, clamping performance under standardized surge waveforms, moisture sensitivity level (MSL 1), and direct alternatives for automotive and industrial power rail protection design.
Technical Context
The SMAJ40CH implements a glass-passivated silicon junction optimized for fast transient response (<1.0 ps from 0 V to VBR min) and low leakage (<1 µA at 40 V). Its unidirectional configuration provides asymmetric clamping-forward conduction limited to 3.5 V at 25 A-while maintaining bidirectional surge immunity per ISO 7637-2 compliance.
Thermal design is enabled by a 150 °C maximum junction temperature rating and 1 W steady-state power dissipation capability. The device operates across –55 °C to +150 °C and meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability requirements for molded compound.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous reverse operating voltage before leakage exceeds 1 µA; defines safe DC bias margin for protected line. |
| VBR @ IT=1 mA | 44.4–54.3 V - Breakdown voltage range confirming reliable turn-on during overvoltage events without premature conduction. |
| VC @ IPPM=5.6 A | 71.4 V - Clamping voltage under 10/1000 µs surge; limits downstream IC stress to ≤71.4 V during 400 W transient. |
| PPPM | 400 W - Peak pulse power handling per 10/1000 µs waveform; supports robust protection against load dump and inductive switching spikes. |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off voltage; ensures minimal standby power loss and signal integrity in high-impedance circuits. |
| TJ max | 150 °C - Maximum junction temperature; enables operation in under-hood automotive environments and thermally constrained PCB layouts. |
Pinout & Package
DO-214AC (SMA) surface-mount package: 2-terminal, single-die unidirectional TVS with cathode band marking; matte tin-plated leads compliant with J-STD-002 solderability; 0.060 g typical weight; MSL Level 1 per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input reference node for unidirectional clamping | Connected to protected line; conducts forward surge current up to 40 A (8.3 ms half-sine) when clamped. |
| Cathode | Clamping output / ground return path | Connected to system ground or low-impedance return; establishes 71.4 V clamping ceiling during reverse transient events. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control units, body electronics, and ADAS power supplies. |
| Glass passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure. |
| ISO 7637-2 compliance | Withstands Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) without degradation. |
| Fast response time | <1.0 ps rise-to-breakdown enables clamping before sensitive downstream circuitry experiences overvoltage stress. |
| RoHS & halogen-free | Meets IEC 61249-2-21 and EU RoHS Directive; suitable for environmentally regulated automotive and industrial production. |
Applications
| Automotive On-Board DC/DC Converter | Industrial Switching Mode Power Supply |
|---|---|
Use Scenario: Protects 12 V input rail of buck converter powering infotainment MCU against load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed at converter input to clamp transients before they reach controller IC and MOSFET gate drivers. Use Value: Limits voltage excursion to ≤71.4 V during 400 W ISO 7637-2 Pulse 5a events, preventing latch-up or gate oxide damage in downstream ICs. |
Use Scenario: Shields primary-side rectifier output in 48 V telecom SMPS from switching noise and cross-talk-induced surges. IC Role / Device Role / Timing Role: Standoff-rated TVS absorbing repetitive 10/1000 µs transients generated by high-frequency MOSFET switching and transformer leakage. Use Value: Maintains <1 µA leakage at 40 V stand-off, avoiding efficiency loss while delivering 400 W peak suppression without derating below 78 V. |
| LED Driver Power Input Stage | Adapter Secondary-Side Output Protection |
Use Scenario: Secures constant-current LED driver input against ESD and lightning-induced surges in outdoor lighting systems. IC Role / Device Role / Timing Role: Front-end TVS absorbing fast-rising transients before they propagate into current-sense amplifier and PWM controller. Use Value: Clamps 5.6 A surge within 1.0 ps, limiting voltage overshoot to 71.4 V and preserving LED string integrity and driver IC lifetime. |
Use Scenario: Guards USB-C PD adapter secondary-side 20 V output against hot-plug transients and cable discharge events. IC Role / Device Role / Timing Role: Unidirectional suppressor placed between secondary rectifier and output capacitor to prevent overvoltage at USB-PD controller inputs. Use Value: Provides 40 V working stand-off with 71.4 V clamping ceiling - compatible with 20 V ±10% output tolerance and avoids false triggering during normal regulation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40AHT | Lower VBR range (44.4–49.1 V); tighter 5% VWM/VBR ratio; same DO-214AC package and 400 W rating. | Better suited for designs requiring lower clamping onset threshold and tighter voltage margin control. | Select SMAJ40AHT where reduced VBR spread improves consistency in multi-unit parallel configurations. |
| SMBJ40CH | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; higher thermal mass; 600 W PPPM rating. | Preferred for higher-reliability or extended-life applications where board space permits larger footprint and enhanced surge endurance is required. | Choose SMBJ40CH when 600 W peak power handling or improved thermal derating above 25 °C is critical. |
Compared with SMAJ40CH, SMAJ40AHT offers tighter breakdown tolerance for precision clamping, while SMBJ40CH provides higher surge capacity and thermal robustness in a larger package - both serve distinct design priorities without pin-to-pin compatibility.
Availability
SMAJ40CH is available at Aetrix Electronics and suitable for automotive power management, industrial SMPS, LED driver protection, and adapter output stage applications requiring stable component supply with AEC-Q101 qualification and ISO 7637-2 compliance.
Supply support for SMAJ40CH 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, MOSFETs, and power management devices since 1979.
The SMAJ series was developed specifically for automotive and industrial transient suppression, emphasizing AEC-Q101 reliability, fast response, and standardized ISO 7637-2 surge immunity in compact surface-mount packages.
FAQ
What is the clamping voltage of SMAJ40CH under standard 10/1000 µs surge conditions?
The SMAJ40CH has a maximum clamping voltage (VC) of 71.4 V at 5.6 A peak impulse current (IPPM) under the 10/1000 µs waveform. This value is measured per Fig.5 in the official Taiwan Semiconductor datasheet and defines the upper voltage limit imposed on protected circuitry during transient events - critical for ensuring downstream ICs remain within absolute maximum ratings.
Is SMAJ40CH qualified for automotive use?
Yes, SMAJ40CH is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b standards. Its DO-214AC package, MSL Level 1 rating, and operating junction temperature range of –55 °C to +150 °C confirm suitability for under-hood and chassis-mounted automotive electronics where reliability under thermal and electrical stress is mandatory.
What is the reverse leakage current specification for SMAJ40CH at its working stand-off voltage?
SMAJ40CH exhibits a maximum reverse leakage current (IR) of 1 µA at its 40 V working stand-off voltage (VWM). This low leakage ensures minimal power loss in always-on automotive modules and preserves signal integrity in high-impedance sensing nodes - verified per the Electrical Specifications table in the Taiwan Semiconductor datasheet Version A2102.
Does SMAJ40CH have bidirectional or unidirectional polarity?
SMAJ40CH is a unidirectional TVS diode, indicated by the "CH" suffix and cathode band marking per the DO-214AC package outline. It clamps only in reverse bias and conducts forward current up to 40 A (8.3 ms half-sine), unlike "CAH" variants which are bidirectional. This polarity is confirmed in the "Devices for Bipolar Applications" section of the datasheet.
What is the peak pulse power rating of SMAJ40CH and how does it vary with ambient temperature?
SMAJ40CH is rated for 400 W peak pulse power (PPPM) at TA = 25 °C using the 10/1000 µs waveform. Power derating follows the curve in Fig.2 of the datasheet: at 85 °C ambient, usable PPPM drops to approximately 280 W; at 125 °C, it falls to ~160 W - essential for thermal-aware layout in enclosed automotive enclosures.
SMAJ40CH 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):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 71.4V
- Current - Peak Pulse (10/1000µs):
- 5.6A
- 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)
SMAJ40CH FAQ
1.How can I place an order for SMAJ40CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ40CH 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 SMAJ40CH reliable?
The price and inventory of SMAJ40CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ40CH is usually 5 days.
3.What payment methods are accepted for SMAJ40CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ40CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ40CH?
SMAJ40CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ40CH 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 SMAJ40CH?
For technical support, including SMAJ40CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ40CH requirements.
6.How does Aetrix verify that SMAJ40CH is sourced from the original manufacturer or authorized distributors?
All SMAJ40CH 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 SMAJ40CH meets industry standards.
7.What is the process for return or replacement of SMAJ40CH?
All SMAJ40CH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ40CH, 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 SMAJ40CH part is unused and in its original packaging.
Return procedure for SMAJ40CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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