My Inquiry
My Account
Taiwan Semiconductor Corporation SMAJ40
- Part No.:
- SMAJ40
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ40.pdf
- Description:
- 400W, 49.4V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:7,147
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SMAJ40 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 pulse current. It protects DC/DC converters and SMPS inputs against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMAJ40 datasheet, SMAJ40 pinout, SMAJ40 application, or SMAJ40 equivalent, key selection criteria include clamping performance under 10/1000 µs surge, junction temperature derating above 25°C, unidirectional polarity marking, and compliance with J-STD-020 Level 1 moisture sensitivity for automated reflow assembly.
Technical Context
The SMAJ40 operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its VBR range (44.4–54.3 V @ 1 mA). Its glass-passivated junction ensures stable breakdown and low leakage (<1 µA @ 40 V), while fast response (<1.0 ps) enables suppression of sub-nanosecond ESD and switching-induced spikes.
It delivers 400 W peak pulse power (10/1000 µs waveform) up to TA = 25°C, derating linearly per Fig.2; steady-state power dissipation is 1 W, and maximum junction temperature is 150°C. Polarity is marked by cathode band; bidirectional variants use "CA" suffix (e.g., SMAJ40CA), not applicable to SMAJ40.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous reverse operating voltage before conduction begins; defines system bus voltage compatibility. |
| VBR min/max | 44.4 V / 54.3 V @ 1 mA - Breakdown threshold range; ensures reliable turn-on margin above VWM. |
| VC @ IPPM | 71.4 V @ 5.6 A - Clamped voltage during 10/1000 µs surge; determines protected circuit's overvoltage stress level. |
| PPPM | 400 W - Peak pulse power handling (10/1000 µs); supports automotive load dump and ISO 7637-2 Pulse 5a simulation. |
| IR @ VWM | <1 µA - Reverse leakage at 40 V; minimizes standby power loss in high-impedance monitoring circuits. |
| TJ max | 150 °C - Maximum junction temperature; sets thermal design limits for PCB copper area and ambient airflow. |
Pinout & Package
DO-214AC (SMA) surface-mount package: single-ended, two-terminal device with cathode band marking polarity. Matte tin-plated leads meet J-STD-002 solderability; weight ≈0.060 g; UL 94V-0 molding compound.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Reverse voltage reference | Connected to lower-potential node (e.g., GND or return path); defines directionality of protection. |
| Cathode (marked) | Reverse voltage input / Clamping node | Connected to protected line (e.g., +40 V rail); conducts avalanche current to anode during overvoltage events. |
Key Features
| Feature | Design Value |
|---|---|
| Glass passivated junction | Ensures stable VBR tolerance and long-term reliability under repeated surge stress without parameter drift. |
| Fast response time <1.0 ps | Enables suppression of nanosecond-scale EFT/burst transients before sensitive ICs experience latch-up or gate oxide damage. |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Validated for automotive electronics protection including battery line transients, ignition noise, and load dump coupling paths. |
| J-STD-020 Level 1 moisture sensitivity | Permits standard SMT reflow without baking; eliminates pre-conditioning steps and reduces manufacturing cycle time. |
Applications
| Switching Mode Power Supply (SMPS) | On-board DC/DC Converter |
|---|---|
Use Scenario: Input stage protection against line surges and back-EMF from upstream converters. IC Role / Device Role / Timing Role: Unidirectional TVS clamping element placed between input rail and ground. Use Value: Limits transient voltage to ≤71.4 V during 400 W 10/1000 µs pulses, preventing MOSFET gate oxide failure and controller IC reset. | Use Scenario: Output rail protection in point-of-load (POL) converters powering FPGAs or microcontrollers. IC Role / Device Role / Timing Role: Secondary-side transient suppressor on regulated 5–12 V outputs. Use Value: Maintains output stability during hot-swap events or inductive kickback, with <1 µA leakage preserving light-load efficiency. |
| Automotive Lighting Module | Industrial Adapter Interface |
Use Scenario: LED driver input protection against load dump and jump-start transients in headlamp control units. IC Role / Device Role / Timing Role: Primary transient clamp on 12 V or 24 V supply line before DC/DC regulation. Use Value: Withstands ISO 7637-2 Pulse 5a-equivalent energy (derated per Fig.2), enabling AEC-Q200-aligned designs without external snubbers. | Use Scenario: AC/DC adapter secondary-side output protection for USB-C PD or PoE-powered devices. IC Role / Device Role / Timing Role: Standoff-rated TVS on isolated low-voltage output (e.g., 5 V, 9 V, 12 V). Use Value: 40 V VWM matches common adapter output rails; 71.4 V VC ensures downstream USB interface ICs remain within absolute maximum ratings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40A | Narrower VBR range (44.4–49.1 V) and lower VC (64.5 V @ 6.2 A); same PPPM, package, and polarity. | Better clamping margin for 40 V systems with tight voltage tolerances; slightly higher IPPM rating. | Select SMAJ40A when tighter VBR distribution and lower clamping voltage are required for robust 40 V rail protection. |
| SMBJ40 | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; 600 W PPPM (10/1000 µs). | Higher power handling and thermal mass; requires larger PCB footprint and different pad layout. | Choose SMBJ40 only if system-level surge testing exceeds 400 W or thermal constraints demand higher steady-state dissipation capability. |
Compared with SMAJ40A, the SMAJ40 offers wider VBR tolerance and higher clamping voltage-suitable for less critical 40 V rails where cost and board space are prioritized. Against SMBJ40, it trades power headroom for compact DO-214AC footprint and lower assembly cost in space-constrained adapters and lighting modules.
Availability
SMAJ40 is available at Aetrix Electronics and suitable for switching mode power supplies, automotive lighting modules, and industrial adapter interfaces requiring stable component supply across production lifecycles.
Supply support for SMAJ40 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.
The SMAJ series was designed specifically for surface-mount transient suppression in automotive, industrial, and consumer power electronics, emphasizing ISO 7637-2 compliance, J-STD-020 Level 1 process compatibility, and tight parametric consistency across voltage grades.
FAQ
What is the maximum clamping voltage of the SMAJ40 under standard test conditions?
The SMAJ40 has a maximum clamping voltage (VC) of 71.4 V when subjected to a 10/1000 µs waveform with a peak pulse current (IPPM) of 5.6 A. This value is measured at TA = 25°C and defines the upper voltage limit imposed on protected circuitry during surge events. The SMAJ40 maintains this clamping performance across its specified operating temperature range, with derating applied above 25°C per the manufacturer's pulse derating curve.
Is the SMAJ40 suitable for bidirectional transient protection?
No, the SMAJ40 is a unidirectional TVS diode, intended for protection of DC lines with defined polarity. Its cathode band marking indicates the terminal that connects to the protected line. For bidirectional applications-such as AC signal lines or differential buses-engineers must select the SMAJ40CA variant, which features symmetrical breakdown in both directions. Using SMAJ40 in bidirectional configurations risks incomplete clamping during positive half-cycles.
What packaging and moisture sensitivity level does the SMAJ40 have?
The SMAJ40 is supplied in DO-214AC (SMA) surface-mount package, packaged 7,500 units per tape-and-reel. It meets J-STD-020 Moisture Sensitivity Level 1, meaning it can be mounted using standard reflow profiles without prior baking. This eliminates moisture-related popcorning risk and simplifies SMT line integration-critical for high-volume adapter and lighting module production where floor life and process repeatability are essential.
How does the SMAJ40 compare to the SMAJ40A in terms of electrical performance?
The SMAJ40A offers a tighter breakdown voltage range (44.4–49.1 V vs. 44.4–54.3 V for SMAJ40) and lower clamping voltage (64.5 V vs. 71.4 V at rated IPPM). Both share identical VWM (40 V), PPPM (400 W), and package. The SMAJ40A's improved clamping margin makes it preferable for 40 V systems with narrow voltage windows, while SMAJ40 provides broader VBR tolerance for cost-sensitive, less stringent applications.
Does the SMAJ40 comply with automotive transient immunity standards?
Yes, the SMAJ40 is explicitly rated to meet ISO 7637-2 for automotive transient immunity, covering Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupled noise). Its 400 W peak pulse power rating, fast <1.0 ps response, and 150°C junction rating align with AEC-Q200 stress requirements when used within derated thermal limits. However, full AEC-Q200 qualification requires additional qualification testing by the end customer.
SMAJ40 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:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ40 FAQ
1.How can I place an order for SMAJ40 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ40 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 SMAJ40 reliable?
The price and inventory of SMAJ40 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ40 is usually 5 days.
3.What payment methods are accepted for SMAJ40?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ40 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ40?
SMAJ40 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ40 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 SMAJ40?
For technical support, including SMAJ40 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ40 requirements.
6.How does Aetrix verify that SMAJ40 is sourced from the original manufacturer or authorized distributors?
All SMAJ40 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 SMAJ40 meets industry standards.
7.What is the process for return or replacement of SMAJ40?
All SMAJ40 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ40, 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 SMAJ40 part is unused and in its original packaging.
Return procedure for SMAJ40:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ40 Tags
-
ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
-
D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
-
DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
-
D5V0L1B2WS-7
Diodes Incorporated
Tech Hub
Comparator circuit design covering voltage thresholds, input limits, open-collector outputs, LM393 wiring, op-amp differences, hysteresis, timing, window detection and practical fault diagnosis.
Schmitt triggers use separate rising and falling thresholds to stabilize slow or noisy signals. This guide covers hysteresis, 74HC14 and 74HCT14 selection, comparator calculations, RC oscillators and p…
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
