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Vishay General Semiconductor - Diodes Division SMAJ28A-E3/61
- Part No.:
- SMAJ28A-E3/61
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28A-E3/61.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SMAJ28A-E3/61 from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode designed for primary overvoltage protection of sensitive ICs, MOSFETs, and signal lines. It features a 28 V standoff 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 a 10/1000 μs waveform - deployed in consumer, industrial, and automotive electronics against inductive switching transients and ESD.
For engineers reviewing the SMAJ28A-E3/61 datasheet, SMAJ28A-E3/61 pinout, SMAJ28A-E3/61 application, or SMAJ28A-E3/61 equivalent, key selection criteria include its unidirectional polarity, SMA (DO-214AC) package compatibility with automated placement, AEC-Q101 qualification eligibility (via HE3 suffix), and verified clamping performance under repetitive surge conditions per IEC 61000-4-5.
Technical Context
This TVS diode operates as a fast-acting shunt protector: when reverse voltage exceeds VWM = 28 V, it transitions from high-impedance blocking to low-impedance conduction within <1 ps, clamping transient energy to ≤45.4 V at 8.8 A. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1.0 μA at VWM).
Thermal design relies on RθJA = 120 °C/W (typ.) and RθJL = 30 °C/W (typ.), requiring minimum 0.2" × 0.2" copper pads per terminal for rated 400 W pulse handling. The device is rated for TJ = –55 to +150 °C and 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 significant leakage; defines system-level DC rail protection threshold. |
| VBR (min/max) | 31.1 V / 34.4 V at IT = 1 mA - Confirmed breakdown range ensures reliable turn-on margin above VWM without premature conduction. |
| VC @ IPPM | 45.4 V at 8.8 A - Clamped voltage during 10/1000 μs surge; determines maximum stress imposed on downstream protected circuitry. |
| PPPM | 400 W - Peak pulse power rating with 10/1000 μs waveform; validates capability to absorb defined lightning/surge energy per IEC 61000-4-5. |
| IFSM | 40 A - Non-repetitive forward surge current (8.3 ms half-sine); supports robustness against accidental polarity reversal events. |
| TJ max. | +150 °C - Maximum junction temperature; enables operation in under-hood automotive or high-ambient industrial environments. |
| Package | SMA (DO-214AC) - Standardized surface-mount outline with cathode band marking; compatible with JEDEC MS-013 and IPC-7351B footprints. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated compound, polarity indicated by cathode band on unidirectional types.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / transient return path | Connected to system ground or low-side reference; completes clamping loop during overvoltage events. |
| Cathode | Reverse-biased terminal / protected line connection | Connected to the line being protected (e.g., 28 V supply rail or signal trace); blocks normal operation, conducts during transients. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Validated energy absorption capacity for IEC 61000-4-5 Level 3/4 surge immunity compliance in industrial and automotive designs. |
| Low clamping ratio (VC/VBR ≈ 1.36) | Minimizes voltage overshoot during clamping, reducing risk of latch-up or gate oxide damage in protected MOSFETs and logic ICs. |
| Glass passivated junction | Ensures long-term stability of VBR and leakage under thermal cycling and humidity exposure per JESD22-A101. |
| MSL Level 1, 260 °C reflow compatible | Enables single-pass lead-free assembly without popcorn cracking or delamination concerns in high-volume SMT production. |
| AEC-Q101 qualification option (HE3/HM3) | Supports automotive-grade sourcing via alternate suffixes - critical for ADAS, body control, and infotainment subsystems requiring reliability validation. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 24 V CAN bus power rails and microcontroller supply inputs from load dump and alternator ripple transients. IC Role / Device Role / Timing Role: Unidirectional shunt TVS placed between VBAT and GND, conducting only during positive-going surges exceeding 28 V. Use Value: Limits clamped voltage to 45.4 V, ensuring downstream 3.3 V/5 V regulators and CAN transceivers remain within absolute maximum ratings during ISO 7637-2 Pulse 5a events. |
Use Scenario: Safeguarding analog sensor outputs (e.g., pressure, temperature) connected to ADC inputs in PLC modules exposed to field wiring transients. IC Role / Device Role / Timing Role: Low-capacitance TVS mounted directly at connector entry point, suppressing fast-rising EFT bursts (IEC 61000-4-4) before signal conditioning stages. Use Value: Sub-1 ps response time and 45.4 V clamping prevent ADC saturation and data corruption while maintaining signal integrity up to 1 MHz bandwidth. |
| Consumer USB Power Delivery Line | Telecom Ethernet PHY Protection |
|
Use Scenario: Overvoltage protection on 5 V/9 V/15 V USB PD input rails in portable chargers and power banks subjected to hot-plug and adapter fault conditions. IC Role / Device Role / Timing Role: Primary front-end TVS on input stage, coordinated with secondary polymer PTC for overcurrent limiting. Use Value: 400 W pulse rating absorbs multiple 10/1000 μs surges without degradation, supporting >50,000 connect/disconnect cycles per JEDEC JESD22-A114. |
Use Scenario: Secondary-level protection on 3.3 V bias rails feeding Ethernet PHY ICs in PoE-powered switches and access points. IC Role / Device Role / Timing Role: Unidirectional clamp referenced to local 3.3 V plane, suppressing induced surges from cable coupling or nearby lightning strikes. Use Value: 1.0 μA max leakage at 28 V ensures minimal quiescent current impact on always-on management circuits and maintains PoE Class 3/4 power budget integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A-M3/61 | Halogen-free, RoHS-compliant variant with identical electrical specs and SMA package; same thermal and surge ratings. | No functional difference; selected where halogen-free material compliance is mandated by OEM environmental policy (e.g., EU WEEE, China RoHS II). | Direct drop-in replacement for SMAJ28A-E3/61 when halogen-free bill-of-materials is required. |
| SMAJ28CA-E3/61 | Bidirectional version with symmetric 28 V standoff and matched VBR in both directions; otherwise identical package and power rating. | Required for AC-coupled or floating signal lines (e.g., RS-485, audio) where polarity reversal or bidirectional transients occur. | Substitute only when bidirectional clamping is needed; not interchangeable in unidirectional DC rail applications due to doubled leakage path. |
Compared with SMAJ28A-E3/61, the SMAJ28A-M3/61 offers identical protection performance with halogen-free construction, while SMAJ28CA-E3/61 provides symmetrical clamping essential for AC or differential signaling - neither is pin-compatible without verifying board-level polarity and grounding topology.
Availability
SMAJ28A-E3/61 is available at Aetrix Electronics and suitable for automotive power rail protection, industrial sensor interface hardening, consumer USB PD input staging, and telecom PHY bias rail safeguarding requiring stable component supply across multi-year production programs.
Supply support for SMAJ28A-E3/61 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 was engineered for high-energy transient suppression in space-constrained surface-mount applications, targeting automotive, industrial, and communications systems where robustness against ISO 7637-2 and IEC 61000-4-x threats is mandatory.
FAQ
What is the maximum clamping voltage of the SMAJ28A-E3/61 under standard test conditions?
The SMAJ28A-E3/61 has a maximum clamping voltage (VC) of 45.4 V at 8.8 A peak pulse current with a 10/1000 μs waveform. This value is measured per IEC 61000-4-5 and defines the upper voltage limit imposed on protected circuitry during surge events. The SMAJ28A-E3/61 maintains this clamping performance across its full operating temperature range of –55 °C to +150 °C.
Is the SMAJ28A-E3/61 suitable for automotive applications requiring AEC-Q101 qualification?
The SMAJ28A-E3/61 itself is not AEC-Q101 qualified; however, Vishay offers the functionally identical SMAJ28AHE3_A variant (with HE3 suffix) that is fully AEC-Q101 qualified for automotive use. The SMAJ28A-E3/61 shares the same electrical specifications, package, and thermal behavior but lacks the extended reliability testing required for automotive grade. For production automotive designs, specify SMAJ28AHE3_A instead of SMAJ28A-E3/61.
What is the standoff voltage (VWM) and why is it critical for selecting the SMAJ28A-E3/61?
The SMAJ28A-E3/61 has a standoff voltage (VWM) of 28 V, meaning it remains non-conductive under normal operating conditions up to this DC or RMS voltage. This parameter is critical because VWM must exceed the maximum steady-state voltage of the protected line (e.g., 24 V nominal automotive rail) while providing sufficient margin below VBR to avoid leakage-induced heating. Selecting SMAJ28A-E3/61 for a 24 V system ensures reliable blocking during normal operation and precise turn-on during transients.
How does the SMAJ28A-E3/61 differ from the bidirectional SMAJ28CA-E3/61?
The SMAJ28A-E3/61 is unidirectional with cathode-band polarity and conducts only during positive surges relative to its anode, whereas the SMAJ28CA-E3/61 is bidirectional with symmetrical breakdown in both directions and no polarity marking. Both share identical VWM, PPPM, and package, but SMAJ28CA-E3/61 exhibits double the reverse leakage at VWM. The SMAJ28A-E3/61 is used on DC rails; SMAJ28CA-E3/61 is reserved for AC, differential, or floating lines like RS-485 or antenna feeds.
What PCB layout practices are recommended to achieve the full 400 W rating of the SMAJ28A-E3/61?
To achieve the rated 400 W peak pulse power, the SMAJ28A-E3/61 must be mounted on minimum 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal, per Vishay's datasheet Fig. 1 derating curve. Thermal vias under pads, internal ground/power planes, and short, wide traces reduce impedance and improve heat dissipation. Using smaller pads or insufficient copper area reduces effective PPPM to 300 W or lower - the SMAJ28A-E3/61 will still function but with diminished surge margin.
SMAJ28A-E3/61 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-E3/61 FAQ
1.How can I place an order for SMAJ28A-E3/61 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28A-E3/61 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-E3/61 reliable?
The price and inventory of SMAJ28A-E3/61 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28A-E3/61 is usually 5 days.
3.What payment methods are accepted for SMAJ28A-E3/61?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28A-E3/61 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28A-E3/61?
SMAJ28A-E3/61 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28A-E3/61 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-E3/61?
For technical support, including SMAJ28A-E3/61 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28A-E3/61 requirements.
6.How does Aetrix verify that SMAJ28A-E3/61 is sourced from the original manufacturer or authorized distributors?
All SMAJ28A-E3/61 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-E3/61 meets industry standards.
7.What is the process for return or replacement of SMAJ28A-E3/61?
All SMAJ28A-E3/61 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28A-E3/61, 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-E3/61 part is unused and in its original packaging.
Return procedure for SMAJ28A-E3/61:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ28A-E3/61 Tags
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