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Taiwan Semiconductor Corporation SMAJ40H
- Part No.:
- SMAJ40H
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ40H.pdf
- Description:
- TVS DIODE 40VWM 71.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,439
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Product details
Overview
SMAJ40H from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 40 V working stand-off voltage (VWM), 44.4–54.3 V breakdown voltage (VBR), and 71.4 V maximum clamping voltage (VC) at 5.6 A peak impulse current. It delivers fast sub-1 ps response and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive power line protection.
For engineers reviewing the SMAJ40H datasheet, SMAJ40H pinout, SMAJ40H application, or SMAJ40H equivalent, this device is selected for robust overvoltage protection in DC/DC converters, SMPS inputs, lighting ballasts, and automotive body electronics where low leakage (<1 µA @ 40 V), AEC-Q101 qualification, and UL 94V-0 molding are critical design requirements.
Technical Context
The SMAJ40H operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its VBR range of 44.4–54.3 V at 1 mA test current. Its glass-passivated junction ensures stable breakdown and low leakage (<1 µA at VWM = 40 V), while its 10/1000 µs waveform-rated 400 W peak pulse power supports high-energy transients without thermal runaway.
Designed for automotive-grade reliability, it complies with AEC-Q101, JESD201 Class 2 whisker resistance, and moisture sensitivity level 1 (J-STD-020). Its DO-214AC package features matte tin-plated leads, polarity marking via cathode band, and 0.060 g mass - optimized for automated SMT placement and reflow compatibility.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR @ IT=1 mA | 44.4–54.3 V - Breakdown threshold range ensuring reliable turn-on under surge conditions |
| VC @ IPPM=5.6 A | 71.4 V - Clamped voltage during 10/1000 µs transient, limiting downstream IC stress |
| PPPM | 400 W - Peak pulse power handling capability per 10/1000 µs waveform (derates above 25°C) |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves system efficiency in standby and low-power modes |
| Junction Temp Range | −55 °C to +150 °C - Enables operation in under-hood automotive and industrial environments |
| Package | DO-214AC (SMA) - Standardized SMT footprint with cathode band polarity marking |
Pinout & Package
DO-214AC (SMA) package: surface-mount, single-diode configuration with cathode indicated by molded band. Matte tin-plated leads meet J-STD-002 solderability; polarity must be observed during PCB layout to ensure correct unidirectional clamping.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input reference node for clamping path | Connected to protected line (e.g., +12 V rail); conducts only during forward surge events |
| Cathode | Clamping output / ground return | Connected to system ground or low-impedance return path; sinks transient energy during reverse overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control units and body electronics |
| Glass passivated junction | Ensures stable VBR, low leakage drift, and long-term reliability under thermal cycling |
| Fast response time <1 ps | Clamps transients before sensitive downstream circuitry experiences overvoltage damage |
| Meets ISO 7637-2 Pulse 1/2a/2b/3a/3b | Complies with automotive electrical disturbance standards for battery line and load-dump immunity |
| UL 94V-0 molding compound | Provides flame-retardant housing suitable for enclosed power modules and lighting systems |
Applications
| Automotive Body Control Module (BCM) | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting LIN bus interface and power supply rails in door modules, seat controllers, and mirror actuators against load dump and inductive switching spikes. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between battery input and DC/DC regulator input to clamp transients up to 71.4 V. Use Value: Prevents latch-up or permanent damage to buck controller ICs and microcontrollers during ISO 7637-2 Pulse 5a events. | Use Scenario: Safeguarding primary-side input of isolated 24 V-to-5 V DC/DC converters used in PLC I/O modules and motor drives. IC Role / Device Role / Timing Role: Standoff-rated TVS on input rail to absorb repetitive 400 W surges without degradation across −40 °C to +125 °C ambient. Use Value: Eliminates need for external crowbar circuits or redundant fusing due to consistent 400 W 10/1000 µs rating and <1 µA leakage. |
| LED Driver Power Supply | USB-C PD Adapter Secondary Side |
Use Scenario: Overvoltage protection on constant-current LED string drivers exposed to lightning-induced surges in outdoor signage and street lighting. IC Role / Device Role / Timing Role: Primary-line TVS placed after bridge rectifier and before bulk capacitor to limit peak voltage to 71.4 V. Use Value: Maintains compliance with IEC 61000-4-5 Level 3 (2 kV) when combined with appropriate series impedance. | Use Scenario: Secondary-side transient suppression on 20 V PPS output rails of USB-C PD adapters subject to hot-plug and cable ESD events. IC Role / Device Role / Timing Role: Unidirectional clamping device between output rail and ground, rated for 40 V standoff and 71.4 V clamping. Use Value: Ensures USB PD sink ICs (e.g., STUSB4500) remain within absolute maximum ratings during 10/1000 µs surges up to 5.6 A. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40AH | Narrower VBR range (44.4–49.1 V) vs. SMAJ40H (44.4–54.3 V); same VWM, VC, and PPPM | Better consistency for precision-clamp designs where tighter VBR tolerance reduces margin uncertainty | Select SMAJ40AH when VBR uniformity across production lots is prioritized over maximum VBR headroom |
| SMBJ40H | Same electrical specs but in larger DO-214AA (SMB) package; 600 W PPPM rating (vs. 400 W) | Higher power handling suits higher-energy transients; requires larger PCB footprint and different pad layout | Choose SMBJ40H only if system-level testing confirms >400 W surge exposure and board space permits SMB footprint |
Compared with SMAJ40AH and SMBJ40H, the SMAJ40H offers the broadest VBR range among 40 V stand-off TVS diodes in DO-214AC, balancing cost-effective SMT integration with sufficient clamping margin for general-purpose automotive and industrial use - without requiring PCB redesign or derating for thermal dissipation.
Availability
SMAJ40H is available at Aetrix Electronics and suitable for automotive body electronics, industrial DC/DC converter inputs, LED driver power supplies, and USB-C PD adapter secondary-side protection requiring stable component supply and AEC-Q101-compliant sourcing.
Supply support for SMAJ40H 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.
The SMAJ series is part of TSC's AEC-Q101-qualified transient suppression portfolio, engineered specifically for automotive and industrial power line protection where reliability, low leakage, and standardized SMT packaging are mandatory.
FAQ
What is the clamping voltage of SMAJ40H at its rated peak pulse current?
The SMAJ40H has a maximum clamping voltage (VC) of 71.4 V at 5.6 A peak impulse current (IPPM) under the standard 10/1000 µs waveform. This value is measured per JEDEC test conditions and defines the upper voltage limit imposed on protected circuitry during transient events. The SMAJ40H maintains this clamping performance across its full operating temperature range of −55 °C to +150 °C.
Is SMAJ40H suitable for bidirectional transient protection?
No, SMAJ40H is a unidirectional TVS diode and must be used with correct polarity - cathode tied to ground or low-impedance return path. For bidirectional protection, select SMAJ40CH or SMAJ40CAH, which feature symmetrical breakdown in both directions. Using SMAJ40H in reverse-biased configurations outside its specified unidirectional operation risks failure or inadequate clamping.
Does SMAJ40H meet automotive qualification standards?
Yes, SMAJ40H is AEC-Q101 qualified and meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b for automotive electrical disturbances. It also complies with JESD201 Class 2 whisker resistance, J-STD-020 moisture sensitivity level 1, and RoHS/halogen-free requirements per IEC 61249-2-21 - confirming suitability for under-hood and body electronics applications.
What is the maximum steady-state power dissipation for SMAJ40H?
The SMAJ40H has a steady-state power dissipation (PD) rating of 1 W at 25 °C ambient, derated linearly above that temperature per the pulse derating curve in the datasheet. This rating applies only to continuous DC or low-frequency reverse bias conditions - not transient events, where its 400 W peak pulse power (10/1000 µs) governs performance. Exceeding 1 W continuously will cause thermal runaway.
How does the breakdown voltage tolerance of SMAJ40H affect circuit design?
The SMAJ40H specifies a VBR range of 44.4–54.3 V at 1 mA test current, reflecting process variation across production lots. Designers must ensure system overvoltage thresholds (e.g., supervisor IC reset points or regulator OVP limits) remain above 54.3 V to prevent false triggering, while maintaining adequate margin below the 71.4 V clamping voltage. This tolerance necessitates worst-case analysis rather than nominal-value design.
SMAJ40H 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):
- 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)
SMAJ40H FAQ
1.How can I place an order for SMAJ40H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ40H 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 SMAJ40H reliable?
The price and inventory of SMAJ40H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ40H is usually 5 days.
3.What payment methods are accepted for SMAJ40H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ40H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ40H?
SMAJ40H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ40H 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 SMAJ40H?
For technical support, including SMAJ40H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ40H requirements.
6.How does Aetrix verify that SMAJ40H is sourced from the original manufacturer or authorized distributors?
All SMAJ40H 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 SMAJ40H meets industry standards.
7.What is the process for return or replacement of SMAJ40H?
All SMAJ40H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ40H, 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 SMAJ40H part is unused and in its original packaging.
Return procedure for SMAJ40H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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