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Vishay General Semiconductor - Diodes Division SMAJ28A-E3/5A
- Part No.:
- SMAJ28A-E3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28A-E3/5A.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,958
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Product details
Overview
SMAJ28A-E3/5A from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode designed for robust overvoltage protection on DC power rails and signal lines. It features a 28 V stand-off voltage (VWM), 31.1–34.4 V breakdown voltage (VBR) at 1 mA, 45.4 V maximum clamping voltage (VC) at 8.8 A peak pulse current, and 400 W peak pulse power rating with 10/1000 μs waveform - deployed in automotive infotainment power supplies, industrial sensor interfaces, and telecom line cards.
For engineers reviewing the SMAJ28A-E3/5A datasheet, SMAJ28A-E3/5A pinout, SMAJ28A-E3/5A application, or SMAJ28A-E3/5A equivalent, key selection criteria include clamping performance under 8.8 A surge, thermal resistance (RθJA = 120 °C/W), unidirectional polarity marking, SMA (DO-214AC) package compatibility with automated SMT placement, and AEC-Q101 qualification eligibility via HE3/HM3 variants.
Technical Context
This TVS diode operates as a fast-acting shunt clamp during transient events, leveraging a glass-passivated silicon junction to achieve sub-nanosecond response time and low incremental surge resistance. Its unidirectional configuration provides reverse-biased protection only, with cathode band marking and forward voltage drop of 3.5 V at 25 A (per spec note).
The device is rated for 40 A non-repetitive peak forward surge current (IFSM) and supports continuous power dissipation of 3.3 W at 50 °C ambient on infinite heatsink. Junction temperature range spans −55 °C to +150 °C, and it meets MSL Level 1 per J-STD-020 with 260 °C reflow peak.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before clamping initiates; defines safe DC rail margin. |
| VBR min/max | 31.1 V / 34.4 V at 1 mA - Confirmed breakdown threshold range; ensures reliable turn-on above normal operating voltage. |
| VC @ IPPM | 45.4 V at 8.8 A - Clamped voltage during 10/1000 μs surge; determines protected circuit's maximum transient stress. |
| PPPM | 400 W - Peak pulse power handling capability; validates suitability for IEC 61000-4-5 Level 4 surges. |
| IFSM | 40 A - Single half-sine surge rating (8.3 ms); supports motor drive or relay coil switching transients. |
| TJ max | +150 °C - Maximum junction temperature; enables operation in under-hood automotive or enclosed industrial enclosures. |
| RθJA | 120 °C/W - Thermal resistance junction-to-ambient; informs PCB copper pad sizing (0.2" × 0.2") for thermal reliability. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, low-profile case with matte tin-plated leads solderable per J-STD-002. Cathode identified by black band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path) in unidirectional protection configuration. |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 24 V rail); clamps to anode when transient exceeds VWM. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Validates compliance with IEC 61000-4-5 surge immunity requirements for industrial and automotive electronics. |
| Glass passivated chip junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure. |
| MSL Level 1, 260 °C peak reflow | Enables single-pass lead-free reflow assembly without moisture-induced failure risk. |
| AEC-Q101 qualification option | Available via HE3 suffix variant; required for automotive powertrain and body electronics applications. |
| Low incremental surge resistance | Minimizes VC overshoot during fast-rising transients (<1 ns response), improving IC-level ESD/surge margin. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface |
|---|---|
|
Use Scenario: 24 V battery-supplied infotainment head unit exposed to load dump (ISO 7637-2 Pulse 5a) and jump-start surges. IC Role / Device Role / Timing Role: Unidirectional shunt clamp placed between 24 V input and chassis ground to limit rail voltage to ≤45.4 V during 100 ms transients. Use Value: Prevents damage to downstream DC/DC controllers and microcontrollers by holding clamped voltage below their absolute maximum ratings. |
Use Scenario: 4–20 mA current loop transmitter in factory automation, subject to induced lightning surges on field wiring. IC Role / Device Role / Timing Role: TVS placed across loop terminals (supply and return) to divert surge energy before reaching precision DAC and op-amp front-end. Use Value: Maintains signal integrity and avoids latch-up in analog signal chain components during 1 kV/0.5 kΩ IEC 61000-4-5 tests. |
| Telecom Line Card Protection | Consumer Appliance Motor Control |
|
Use Scenario: DC-fed Ethernet switch PoE midspan injector with 48 V input, vulnerable to AC mains coupling and EFT bursts. IC Role / Device Role / Timing Role: Primary clamping device on 48 V input rail, coordinated with upstream fuse and downstream π-filter. Use Value: Limits transient overshoot to <48 V + 45.4 V = 93.4 V, staying within 100 V MOSFET drain-source rating in primary-side FETs. |
Use Scenario: Brushed DC motor driver in smart HVAC blower, where back-EMF spikes exceed 100 V during commutation. IC Role / Device Role / Timing Role: Mounted across motor terminals to clamp inductive kickback and protect H-bridge MOSFETs. Use Value: Absorbs 400 W surge energy without degradation, enabling >100,000 cycle lifetime under repetitive switching stress. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A-M3/5A | Halogen-free, RoHS-compliant variant with identical electrical specs and SMA package. | No functional difference; selected when halogen-free material compliance is mandated (e.g., EU WEEE, specific OEM specs). | Direct substitution where halogen content restrictions apply; same thermal and clamping behavior. |
| SMAJ28AHE3_A/I | AEC-Q101 qualified version with same VWM, VBR, and VC; differs in test reporting and traceability. | Required for automotive applications requiring component-level qualification (e.g., ADAS camera modules, body control units). | Choose when automotive-grade reliability documentation and extended temperature validation are mandatory. |
Compared with SMAJ28A-E3/5A, the M3/5A offers identical protection performance with halogen-free construction, while the HE3_A/I variant adds AEC-Q101 certification for automotive use - neither alters pinout, footprint, or clamping behavior, but addresses distinct compliance and market requirements.
Availability
SMAJ28A-E3/5A is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial sensor interfaces, telecom line cards, and consumer appliance motor controls requiring stable component supply and full traceability.
Supply support for SMAJ28A-E3/5A 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
Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.
The SMAJ series is engineered for high-energy transient suppression in harsh environments - targeting automotive, industrial, and telecom systems where robustness against ISO 7637, IEC 61000-4-5, and EFT events is critical.
FAQ
What is the clamping voltage of SMAJ28A-E3/5A at its rated peak pulse current?
The SMAJ28A-E3/5A has a maximum clamping voltage (VC) of 45.4 V at 8.8 A peak pulse current (IPPM) with a 10/1000 μs waveform. This value is measured under standardized test conditions and defines the upper voltage limit imposed on protected circuits during surge events. The SMAJ28A-E3/5A maintains this clamping performance across its specified operating temperature range.
Is SMAJ28A-E3/5A suitable for automotive applications?
SMAJ28A-E3/5A itself is commercial-grade and not AEC-Q101 qualified; however, the functionally identical SMAJ28AHE3_A/I variant is AEC-Q101 qualified and shares the same electrical characteristics, package, and pinout. For automotive use, specify the HE3 suffix version - SMAJ28A-E3/5A remains suitable for non-automotive applications like industrial controls and telecom infrastructure.
What does the "E3/5A" suffix indicate in SMAJ28A-E3/5A?
The "E3" denotes RoHS-compliant, commercial-grade construction with matte tin-plated leads, while "/5A" specifies packaging in 13-inch diameter plastic tape and reel containing 7500 units. This format supports high-volume SMT assembly and is distinct from the "/61" (7-inch reel, 1800 units) option. The SMAJ28A-E3/5A retains all standard electrical and thermal specifications of the base SMAJ28A series.
How does SMAJ28A-E3/5A differ from bidirectional TVS diodes like SMAJ28CA?
SMAJ28A-E3/5A is unidirectional and protects only against reverse-polarity transients on positive rails, with a marked cathode band. SMAJ28CA is bidirectional and symmetrically clamps both polarities - used in AC-coupled or floating signal lines. Their VWM (28 V) and VC (45.4 V) match, but SMAJ28A-E3/5A cannot replace SMAJ28CA in AC applications without circuit redesign.
What PCB layout guidance applies to SMAJ28A-E3/5A for optimal thermal and surge performance?
For optimal performance, mount SMAJ28A-E3/5A on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal to achieve the rated 400 W pulse power and 120 °C/W RθJA. Minimize trace inductance between the TVS and protected node, and avoid routing high-speed signals near its terminals. The SMAJ28A-E3/5A requires no additional heatsinking under typical surge duty cycles.
SMAJ28A-E3/5A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-214AC, SMA
- Series:
- TransZorb®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 8.8A
- 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)
SMAJ28A-E3/5A FAQ
1.How can I place an order for SMAJ28A-E3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28A-E3/5A 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 SMAJ28A-E3/5A reliable?
The price and inventory of SMAJ28A-E3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28A-E3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ28A-E3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28A-E3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28A-E3/5A?
SMAJ28A-E3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28A-E3/5A 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 SMAJ28A-E3/5A?
For technical support, including SMAJ28A-E3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28A-E3/5A requirements.
6.How does Aetrix verify that SMAJ28A-E3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ28A-E3/5A 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 SMAJ28A-E3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ28A-E3/5A?
All SMAJ28A-E3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28A-E3/5A, 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 SMAJ28A-E3/5A part is unused and in its original packaging.
Return procedure for SMAJ28A-E3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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