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Taiwan Semiconductor Corporation SMAJ51
- Part No.:
- SMAJ51
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51.pdf
- Description:
- 400W, 63V, 10%, UNIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:3,643
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Product details
Overview
SMAJ51 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 51 V working stand-off voltage (VWM), 56.7–69.3 V breakdown voltage (VBR) at 1 mA test current, 91.1 V maximum clamping voltage (VC) at 4.4 A peak impulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - deployed in switching mode power supplies and on-board DC/DC converters.
For engineers reviewing the SMAJ51 datasheet, SMAJ51 pinout, SMAJ51 application, or SMAJ51 equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b transients, DO-214AC (SMA) package compatibility with automated placement, and unidirectional polarity marking for correct PCB orientation.
Technical Context
The SMAJ51 operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology for stable breakdown behavior and low leakage (<1 µA at 51 V). Its fast response time (<1.0 ps from 0 V to VBR min) ensures effective suppression of ESD and surge events before downstream ICs are damaged.
Designed for single-die configuration in DO-214AC (SMA) package, it supports steady-state power dissipation of 1 W and peak forward surge current of 40 A (8.3 ms half-sine), with operating junction temperature range from –55 °C to +150 °C - meeting JESD201 Class 2 whisker resistance and J-STD-020 Level 1 moisture sensitivity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - maximum continuous reverse voltage before significant leakage; defines safe operating DC rail margin |
| VBR min/max | 56.7 V / 69.3 V at 1 mA - guaranteed avalanche initiation window; ensures consistent turn-on across production lots |
| VC @ IPPM | 91.1 V at 4.4 A - clamped voltage during 10/1000 µs surge; determines protected circuit's maximum transient stress |
| PPPM | 400 W - peak pulse power handling per standard 10/1000 µs waveform; validates compliance with ISO 7637-2 Pulse 5a |
| IR @ VWM | <1 µA - reverse leakage at rated stand-off; minimizes quiescent power loss in battery-powered systems |
| Package | DO-214AC (SMA) - industry-standard surface-mount outline; enables high-density layout and reflow compatibility |
Pinout & Package
DO-214AC (SMA) package with cathode band marking for unidirectional polarity. Matte tin-plated leads meet J-STD-002 solderability requirements; weight ≈ 0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND) in unidirectional clamp configuration |
| Cathode | Avalanche conduction terminal | Marked by band; connected to protected line (e.g., +51 V rail); conducts during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure |
| Fast response time <1.0 ps | Enables suppression of sub-nanosecond ESD events before logic-level ICs experience latch-up or gate oxide damage |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Validates robustness against automotive load dump, inductive switching, and battery disconnect transients |
| RoHS & halogen-free (IEC 61249-2-21) | Meets global environmental compliance requirements for industrial and automotive end equipment |
Applications
| Switching Mode Power Supply (SMPS) | On-Board DC/DC Converter |
|---|---|
Use Scenario: Protection of primary-side MOSFET gate drivers and secondary-side rectifier outputs against flyback spikes and cross-talk. IC Role / Device Role: Unidirectional TVS placed across input/output rails to clamp transient overshoot below IC absolute maximum ratings. Use Value: Limits VC to 91.1 V during 400 W surges, preventing damage to 100 V-rated MOSFETs and synchronous rectifiers. | Use Scenario: Safeguarding point-of-load (POL) regulators in telecom base stations and server VRMs from coupling noise and hot-swap transients. IC Role / Device Role: Rail-to-rail clamp on 12 V or 48 V intermediate bus inputs to absorb energy from inductive kickback and supply ripple. Use Value: With 51 V VWM and 91.1 V VC, maintains headroom for 60 V-rated controllers while suppressing >100 V spikes. |
| Lighting Application | Adapters |
Use Scenario: Overvoltage protection in LED driver circuits exposed to lightning-induced surges on AC mains or 24 V DC input lines. IC Role / Device Role: Primary-side TVS on bulk capacitor input to divert surge current away from PWM controller and gate driver ICs. Use Value: 400 W peak power rating sustains multiple 10/1000 µs pulses without degradation, supporting IEC 61000-4-5 Level 3 compliance. | Use Scenario: Input-stage protection in wall-mounted AC/DC adapters subjected to line transients and ESD during plug insertion. IC Role / Device Role: Standoff-rated clamp on secondary-side output (e.g., 5 V, 9 V, 12 V) to prevent overvoltage delivery to connected devices. Use Value: 51 V VWM allows use on 48 V adapter outputs; 91.1 V VC ensures USB PD or legacy device ICs remain within safe operating area. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51A | Narrower VBR range (56.7–62.7 V vs. 56.7–69.3 V); tighter 5% tolerance; same VWM, VC (82.4 V), and PPPM | Better suited for precision-clamp designs where lower VC and tighter VBR reduce margin uncertainty | Select SMAJ51A when clamping consistency and reduced VC are prioritized over cost-sensitive general-purpose use |
| SMBJ51 | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; higher thermal mass; 600 W PPPM rating | Preferred for higher-energy surge environments (e.g., industrial motor drives) where board space permits larger footprint | Choose SMBJ51 only if PCB layout allows DO-214AA and system requires >400 W pulse handling |
Compared with SMAJ51A and SMBJ51, the SMAJ51 offers optimal balance of compact DO-214AC footprint, 400 W surge capability, and broad VBR tolerance - making it ideal for cost-sensitive, space-constrained consumer and computing power rails where ±10% clamping variation is acceptable.
Availability
SMAJ51 is available at Aetrix Electronics and suitable for switching mode power supplies, on-board DC/DC converters, and lighting applications requiring stable component supply, RoHS-compliant sourcing, and tape-and-reel packaging for SMT automation.
Supply support for SMAJ51 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, serving industrial, computing, and automotive markets since 1979.
The SMAJ series is part of TSC's transient voltage suppressor product line, engineered specifically for high-reliability, surface-mount overvoltage protection in power conversion and interface circuits subject to ISO 7637-2 and IEC 61000-4-5 threats.
FAQ
What is the maximum clamping voltage of the SMAJ51 under standard surge conditions?
The SMAJ51 has a maximum clamping voltage (VC) of 91.1 V at 4.4 A peak impulse current, tested with a 10/1000 µs waveform. This value represents the upper limit of voltage seen by downstream circuitry during a standardized surge event, ensuring protected components remain within their absolute maximum voltage ratings. The SMAJ51 achieves this clamping performance while maintaining its 51 V working stand-off voltage and 400 W peak pulse power rating.
Is the SMAJ51 suitable for bidirectional transient protection?
No, the SMAJ51 is a unidirectional TVS diode, indicated by the absence of "C" or "CA" suffix and confirmed by its single cathode band marking. For bidirectional protection, designers must select SMAJ51C or SMAJ51CA variants, which provide symmetrical clamping in both polarities. Using SMAJ51 in bidirectional applications risks failure during negative-going transients, as it lacks reverse avalanche capability.
What package type does the SMAJ51 use, and is it compatible with standard SMT processes?
The SMAJ51 uses the DO-214AC (SMA) surface-mount package, with matte tin-plated leads that comply with J-STD-002 solderability requirements. Its dimensions and thermal profile support standard reflow soldering processes, and its Level 1 moisture sensitivity rating per J-STD-020 eliminates bake requirements prior to assembly - enabling direct use in high-volume automated placement lines without process modification.
How does the SMAJ51 meet automotive transient immunity standards?
The SMAJ51 meets ISO 7637-2 Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) requirements due to its specified clamping behavior, fast response time (<1.0 ps), and validated 400 W peak pulse power rating. Its 91.1 V clamping voltage at 4.4 A ensures protected ECUs and power modules remain within safe operating limits during real-world vehicle electrical disturbances - provided layout minimizes parasitic inductance in the TVS path.
What is the operating temperature range for the SMAJ51, and how does derating affect its surge capability?
The SMAJ51 operates from –55 °C to +150 °C junction temperature. Its peak pulse power rating of 400 W applies only at TA = 25 °C; above this ambient, power must be derated per Figure 2 in the datasheet - e.g., ~320 W at 75 °C ambient. This derating ensures junction temperature remains below 150 °C during surge events, preserving device integrity and clamping consistency across extended industrial and automotive temperature ranges.
SMAJ51 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):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 91.1V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- 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)
SMAJ51 FAQ
1.How can I place an order for SMAJ51 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51 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 SMAJ51 reliable?
The price and inventory of SMAJ51 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51 is usually 5 days.
3.What payment methods are accepted for SMAJ51?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51?
SMAJ51 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51 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 SMAJ51?
For technical support, including SMAJ51 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51 requirements.
6.How does Aetrix verify that SMAJ51 is sourced from the original manufacturer or authorized distributors?
All SMAJ51 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 SMAJ51 meets industry standards.
7.What is the process for return or replacement of SMAJ51?
All SMAJ51 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51, 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 SMAJ51 part is unused and in its original packaging.
Return procedure for SMAJ51:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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