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Vishay General Semiconductor - Diodes Division SMAJ28A-M3/5A
- Part No.:
- SMAJ28A-M3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28A-M3/5A.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SMAJ28A-M3/5A from Vishay General 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 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 USB port ESD protection circuits.
For engineers reviewing the SMAJ28A-M3/5A datasheet, SMAJ28A-M3/5A pinout, SMAJ28A-M3/5A application, or SMAJ28A-M3/5A equivalent, key selection criteria include its unidirectional polarity, SMA (DO-214AC) package compatibility with automated SMT assembly, low 1.0 μA reverse leakage at VWM, AEC-Q101 qualification eligibility (via HM3 suffix), and thermal resistance of 120 °C/W (junction-to-ambient).
Technical Context
The SMAJ28A-M3/5A operates as a clamping-type TVS diode: under normal conditions it presents high impedance (>1 MΩ) below VWM = 28 V, then rapidly transitions to low-impedance conduction when transient voltage exceeds VBR (min 31.1 V). Its glass-passivated junction ensures stable breakdown characteristics and fast response time (<1 ns) to ESD and lightning-induced surges.
It is rated for 400 W peak pulse power (10/1000 μs) up to TA = 25 °C, derating linearly above that temperature per Fig. 2; maximum junction temperature is +150 °C, and it meets J-STD-020 MSL Level 1 with peak reflow temperature of 260 °C. The cathode band identifies polarity on the SMA package, critical for correct orientation in series-connected protection schemes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before significant leakage; defines safe DC rail margin for 24 V systems. |
| VBR (min/max) | 31.1 V / 34.4 V at IT = 1 mA - Confirmed breakdown range ensures reliable triggering without premature conduction. |
| VC @ IPPM | 45.4 V at 8.8 A - Clamped voltage during 10/1000 μs surge; protects downstream ICs rated ≤45 V absolute max. |
| IPPM | 8.8 A - Peak surge current capability with 10/1000 μs waveform; supports IEC 61000-4-5 Level 3 (1 kV/2 Ω) compliance. |
| PPPM | 400 W - Peak pulse power handling; enables protection against inductive switching transients in motor drivers and solenoid controls. |
| RθJA | 120 °C/W - Junction-to-ambient thermal resistance; requires ≥5.0 mm × 5.0 mm copper pads per terminal for full power rating. |
| TJmax | +150 °C - Maximum junction temperature; supports operation in under-hood automotive environments. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, halogen-free, RoHS-compliant, matte tin-plated leads. Dimensions: 4.93 mm × 3.99 mm × 2.29 mm (L × W × H); cathode band denotes terminal 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Anode-side connection point in unidirectional configuration | Connected to protected line (e.g., VIN); clamps to ground when transient exceeds VBR. |
| Anode (non-banded end) | Reference/return path | Typically tied to system ground or low-impedance return plane; completes clamping path during overvoltage events. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Enables single-device protection against severe transients like ISO 7637-2 Pulse 1/2a/5a in 12 V automotive systems. |
| Low clamping ratio (VC/VBR ≈ 1.43) | Minimizes let-through voltage stress on downstream MOSFETs or microcontrollers during surge events. |
| MSL Level 1, 260 °C peak reflow | Supports standard lead-free reflow profiles without moisture-related popcorn failure or delamination. |
| AEC-Q101 qualification option (HM3 suffix) | Validates reliability for automotive applications including engine control modules and ADAS sensor interfaces. |
| Glass passivated junction | Ensures stable VBR tolerance and long-term leakage stability across temperature and lifetime. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 24 V supply lines in vehicle body control modules from load dump and inductive kickback. IC Role / Device Role / Timing Role: Unidirectional clamping TVS placed between battery rail and DC-DC input, referenced to chassis ground. Use Value: Limits transient voltage to ≤45.4 V, preventing damage to 36 V-rated buck converters and CAN transceivers. |
Use Scenario: Safeguarding analog outputs of pressure sensors in PLC I/O modules exposed to field wiring surges. IC Role / Device Role / Timing Role: Low-capacitance TVS on 4–20 mA loop output, shunting transients before op-amp output stage. Use Value: Maintains signal integrity with <1.0 μA leakage at 28 V, avoiding offset errors in precision current loops. |
| USB Type-A Port ESD Protection | Motor Drive Gate Driver Supply Clamp |
|
Use Scenario: Secondary-level ESD protection on VBUS line of USB host ports in embedded gateways and docking stations. IC Role / Device Role / Timing Role: Standoff-rated TVS upstream of polyfuse and load switch, clamping ±15 kV contact discharge per IEC 61000-4-2. Use Value: Fast <1 ns response captures ESD energy before it reaches USB controller PHY, with no data-line capacitance penalty. |
Use Scenario: Overvoltage clamp on isolated 15 V gate drive supply feeding SiC MOSFET half-bridges in servo inverters. IC Role / Device Role / Timing Role: Unidirectional TVS from gate driver VDD to GND, absorbing Miller-induced spikes during high dV/dt switching. Use Value: 45.4 V clamping prevents gate oxide rupture on 20 V-rated gate drivers while surviving repetitive 400 W pulses. |
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-E3/5A | Same electrical specs; RoHS-compliant but not halogen-free; uses matte tin plating per J-STD-002. | Approved for commercial-grade industrial equipment where halogen-free mandate does not apply. | Select when cost sensitivity outweighs halogen-free requirement and AEC-Q101 is not needed. |
| SMAJ28CA-M3/5A | Bidirectional variant; symmetric VBR (31.1–34.4 V) in both directions; same VC, PPPM, and package. | Required for AC-coupled signal lines (e.g., RS-485, CAN FD) or floating DC buses needing bidirectional clamping. | Choose only if circuit lacks defined polarity or must suppress transients on differential pairs without ground reference. |
Compared with SMAJ28A-M3/5A, the E3 variant offers identical protection performance at lower material cost but excludes halogen-free compliance, while the 28CA variant enables bidirectional clamping essential for differential signaling - neither is pin-compatible for unidirectional use cases without layout revision.
Availability
SMAJ28A-M3/5A is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor interfaces, and USB power rail protection requiring stable component supply, halogen-free compliance, and AEC-Q101 qualification readiness.
Supply support for SMAJ28A-M3/5A 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, TVS devices, and optoelectronics with emphasis on reliability, power efficiency, and automotive-grade validation.
The SMAJ series is engineered for high-energy transient suppression in harsh environments - targeting 12 V/24 V automotive, industrial automation, and telecom infrastructure where robustness and repeatable clamping are critical.
FAQ
What is the maximum clamping voltage of the SMAJ28A-M3/5A under a 10/1000 μs surge?
The SMAJ28A-M3/5A has a maximum clamping voltage (VC) of 45.4 V when subjected to its rated peak pulse current of 8.8 A with a 10/1000 μs waveform. This value is measured per IEC 61000-4-5 test conditions and ensures downstream components see no more than 45.4 V during surge events. The SMAJ28A-M3/5A maintains this clamping performance across its specified operating temperature range and is validated with 0.2" × 0.2" copper pads per terminal.
Is the SMAJ28A-M3/5A suitable for automotive applications?
Yes - the SMAJ28A-M3/5A is halogen-free and RoHS-compliant, and its HM3 suffix indicates eligibility for AEC-Q101 qualification (achieved via base P/NHM3_X variants). While the standard SMAJ28A-M3/5A is commercial-grade, it shares identical electrical and thermal specifications with qualified versions and is widely used in non-safety-critical automotive subsystems such as infotainment power rails and body electronics. For certified deployment, specify SMAJ28A-HM3_A/I or equivalent qualified ordering codes.
How does the SMAJ28A-M3/5A differ from the SMAJ28CA-M3/5A?
The SMAJ28A-M3/5A is unidirectional, with polarity marked by a cathode band and intended for DC rail protection where current flows in one direction. The SMAJ28CA-M3/5A is bidirectional, lacking polarity marking and providing symmetrical clamping in both directions - required for AC signals or floating buses. Both share identical VBR, VC, PPPM, and SMA package, but they are not interchangeable without circuit redesign due to polarity and conduction behavior differences.
What is the thermal resistance and recommended PCB layout for full-power operation of the SMAJ28A-M3/5A?
The SMAJ28A-M3/5A has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W, achievable only when mounted on minimum recommended pad layout: 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal, per Vishay Document 88390. Reducing pad area increases RθJA, derating power capability. For sustained surge duty, thermal vias under pads and internal ground planes further improve heat dissipation. The SMAJ28A-M3/5A must not exceed +150 °C junction temperature under worst-case ambient and power conditions.
Does the SMAJ28A-M3/5A meet industry surge immunity standards such as IEC 61000-4-5?
Yes - the SMAJ28A-M3/5A's 400 W peak pulse power rating with 10/1000 μs waveform directly supports compliance with IEC 61000-4-5 Level 3 (1 kV line-to-ground, 2 Ω source impedance). When implemented with proper PCB layout (5.0 mm × 5.0 mm pads, short traces, low-inductance grounding), it clamps transients to ≤45.4 V, protecting downstream ICs rated for 48 V absolute maximum. System-level validation is required, but the SMAJ28A-M3/5A provides the foundational clamping performance needed for certification.
SMAJ28A-M3/5A 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-M3/5A FAQ
1.How can I place an order for SMAJ28A-M3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28A-M3/5A 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-M3/5A reliable?
The price and inventory of SMAJ28A-M3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28A-M3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ28A-M3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28A-M3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28A-M3/5A?
SMAJ28A-M3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28A-M3/5A 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-M3/5A?
For technical support, including SMAJ28A-M3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28A-M3/5A requirements.
6.How does Aetrix verify that SMAJ28A-M3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ28A-M3/5A 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-M3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ28A-M3/5A?
All SMAJ28A-M3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28A-M3/5A, 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-M3/5A part is unused and in its original packaging.
Return procedure for SMAJ28A-M3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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