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Taiwan Semiconductor Corporation SMAJ45
- Part No.:
- SMAJ45
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ45.pdf
- Description:
- 400W, 55.6V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:3,029
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Product details
Overview
SMAJ45 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for robust overvoltage protection in DC power rails. It features a 45 V working stand-off voltage (VWM), 50.0–61.1 V breakdown voltage (VBR) at 1 mA test current, and clamps to ≤80.3 V at 5.0 A peak impulse current under 10/1000 µs waveform - delivering 400 W peak pulse power capability for surge immunity per ISO 7637-2 Pulse 1/2a/2b/3a/3b in automotive and industrial power supplies.
For engineers reviewing the SMAJ45 datasheet, SMAJ45 pinout, SMAJ45 application, or SMAJ45 equivalent, key selection criteria include its unidirectional polarity, glass-passivated junction for stable clamping, <1.0 ps response time, <1 µA reverse leakage above 10 V, and UL 94V-0 molded case - critical for SMPS input protection, on-board DC/DC converters, and lighting driver ESD/surge resilience.
Technical Context
The SMAJ45 operates as a unidirectional avalanche diode with cathode-band polarity marking, leveraging a glass-passivated silicon junction to ensure consistent breakdown behavior and low leakage (<1 µA at VWM = 45 V). Its clamping performance is characterized by VC = 80.3 V at IPPM = 5.0 A (10/1000 µs), enabling effective suppression of fast transients while maintaining low forward voltage drop (VF = 3.5 V at 25 A).
Thermally rated for TJ = –55 °C to +150 °C and housed in a moisture-sensitive level 1 DO-214AC package, the SMAJ45 supports automated SMT placement and meets JESD201 Class 2 whisker resistance and RoHS/halogen-free compliance - making it suitable for high-reliability, high-volume automotive and industrial PCB assemblies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 45 V - Maximum continuous DC or RMS voltage the device blocks without conduction; defines operating rail margin before clamping. |
| VBR min/max | 50.0 / 61.1 V @ 1 mA - Confirmed avalanche onset range; ensures reliable triggering above system nominal voltage. |
| VC @ IPPM | 80.3 V @ 5.0 A (10/1000 µs) - Clamped voltage during worst-case surge; determines protected circuit's maximum transient exposure. |
| PPPM | 400 W - Peak pulse power handling per standard waveform; enables compliance with ISO 7637-2 automotive surge tests. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage at rated stand-off; minimizes standby power loss in always-on systems. |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline with 0.060 g mass and matte tin-plated leads for J-STD-002 solderability. |
Pinout & Package
DO-214AC (SMA) package: single-axis, two-terminal surface-mount device with cathode band marking on one end. Terminals are non-polarized in layout but functionally asymmetric - anode (unmarked end) and cathode (banded end) define unidirectional conduction path.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Reverse voltage reference node | Connected to lower-potential side of protected line (e.g., GND or return path); establishes directionality for transient shunting. |
| Cathode | Clamping output / Surge sink node | Connected to higher-potential rail (e.g., +45 V input); conducts avalanche current during overvoltage to clamp voltage at VC ≤ 80.3 V. |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ps - Enables sub-nanosecond reaction to ESD and lightning-induced transients, protecting downstream ICs before damage occurs. |
| Glass passivated junction | Stable VBR tolerance and low IR drift across temperature and lifetime - critical for long-term reliability in automotive under-hood environments. |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) - meets OEM-level automotive EMC requirements. |
| Moisture sensitivity level 1 | No floor-life limitation or bake requirement before reflow - simplifies SMT manufacturing and reduces assembly cost. |
Applications
| Automotive Power Input Protection | Industrial SMPS Input Stage |
|---|---|
Use Scenario: 12 V/24 V vehicle battery line exposed to load dump (Pulse 5a) and alternator switching spikes (Pulse 2a). IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and DC/DC converter input to clamp transients before they reach primary-side controller. Use Value: With VWM = 45 V and VC = 80.3 V, SMAJ45 protects against ISO 7637-2 Pulse 1 (–150 V) and Pulse 2b (–100 V) without crowbarring, preserving system uptime. |
Use Scenario: AC-DC adapter front-end subjected to line surges and EFT bursts per IEC 61000-4-4/5. IC Role / Device Role / Timing Role: Standoff protector across bulk capacitor input, absorbing repetitive 10/1000 µs surges up to 400 W peak power. Use Value: 400 W PPPM rating and <1 µA IR at 45 V enable high-efficiency operation with no standby current penalty or thermal derating concerns. |
| LED Driver DC Bus Protection | On-Board DC/DC Converter Input |
Use Scenario: Constant-current LED string powered from 48 V intermediate bus in streetlight or signage systems. IC Role / Device Role / Timing Role: Transient suppressor across input terminals of buck LED driver IC to prevent latch-up or gate oxide failure during hot-swap events. Use Value: 80.3 V clamping voltage ensures driver ICs rated for 65 V absolute max survive 48 V rail transients exceeding 100 V peak. |
Use Scenario: Point-of-load (POL) converter in telecom base station board receiving 48 V backplane input. IC Role / Device Role / Timing Role: Primary overvoltage guard on POL input, coordinated with secondary-side TVS for cascaded protection architecture. Use Value: DO-214AC footprint allows dense layout; UL 94V-0 molding compound meets IPC-CC-830B flammability requirements for enclosed equipment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ45A | Narrower VBR range (50.0–55.3 V), lower clamping voltage (VC = 72.7 V @ 5.5 A), tighter tolerance. | Better suited for precision-clamp designs where margin below downstream IC abs-max ratings is minimal. | Select SMAJ45A when clamping voltage headroom is constrained; SMAJ45 offers broader VBR tolerance for cost-sensitive volume production. |
| SMBJ45 | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; 600 W PPPM rating (vs. 400 W). | Higher power handling supports longer surge durations or repeated events; requires larger PCB area. | Choose SMBJ45 only if system-level testing demands >400 W pulse capability; SMAJ45 provides optimal size-power balance for space-constrained boards. |
Compared with SMAJ45A and SMBJ45, the SMAJ45 delivers the best trade-off of compact DO-214AC footprint, certified 400 W surge capacity, and broad VBR tolerance - making it ideal for automotive body control modules and industrial power adapters where layout density and supply-chain consistency are prioritized.
Availability
SMAJ45 is available at Aetrix Electronics and suitable for automotive power input protection, industrial SMPS input stage, and LED driver DC bus protection requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SMAJ45 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 AEC-Q101-compliant automotive and industrial transient suppression, emphasizing glass-passivated reliability, ISO 7637-2 validation, and SMT manufacturability in standard DO-214AC packaging.
FAQ
What is the polarity configuration of the SMAJ45?
The SMAJ45 is a unidirectional TVS diode with clearly marked cathode band on the DO-214AC package. It conducts only when the cathode is at higher potential than the anode - essential for DC rail protection where reverse polarity must be blocked. This differs from bidirectional variants (e.g., SMAJ45CA), which lack polarity marking and conduct symmetrically.
Does the SMAJ45 meet automotive qualification standards?
Yes, the SMAJ45 is designed and tested to meet AEC-Q101 stress requirements for transient voltage suppressors and complies with ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b waveforms. Its –55 °C to +150 °C operating junction temperature range and moisture sensitivity level 1 rating further support automotive under-hood and chassis applications.
What is the maximum clamping voltage of the SMAJ45 under surge conditions?
The SMAJ45 clamps to a maximum of 80.3 V when subjected to a 5.0 A peak impulse current with a 10/1000 µs waveform - verified per standard test conditions in the Taiwan Semiconductor datasheet. This value defines the upper voltage limit imposed on protected circuitry during transient events.
Can the SMAJ45 be used in bidirectional signal-line protection?
No - the SMAJ45 is strictly unidirectional and unsuitable for AC or bidirectional data lines. For such applications, use a bidirectional variant like SMAJ45CA (if available) or select purpose-built bidirectional TVS arrays. Using SMAJ45 on AC signals risks forward conduction and unintended DC path formation.
How does the SMAJ45 compare to the SMAJ45A in terms of electrical performance?
The SMAJ45A has a tighter breakdown voltage range (50.0–55.3 V vs. 50.0–61.1 V) and lower clamping voltage (72.7 V vs. 80.3 V at rated current), offering improved precision for designs with narrow voltage margins. However, the SMAJ45 provides greater VBR tolerance for cost-driven, high-volume applications where minor parameter spread is acceptable.
SMAJ45 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):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 80.3V
- Current - Peak Pulse (10/1000µs):
- 5A
- 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)
SMAJ45 FAQ
1.How can I place an order for SMAJ45 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ45 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 SMAJ45 reliable?
The price and inventory of SMAJ45 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ45 is usually 5 days.
3.What payment methods are accepted for SMAJ45?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ45 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ45?
SMAJ45 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ45 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 SMAJ45?
For technical support, including SMAJ45 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ45 requirements.
6.How does Aetrix verify that SMAJ45 is sourced from the original manufacturer or authorized distributors?
All SMAJ45 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 SMAJ45 meets industry standards.
7.What is the process for return or replacement of SMAJ45?
All SMAJ45 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ45, 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 SMAJ45 part is unused and in its original packaging.
Return procedure for SMAJ45:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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