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Vishay General Semiconductor - Diodes Division SMAJ28CAHE3_A/I
- Part No.:
- SMAJ28CAHE3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28CAHE3_A/I.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,105
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Product details
Overview
SMAJ28CAHE3_A/I from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection on signal and power 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 10/1000 μs waveform - deployed in automotive sensor interfaces, industrial I/O protection, and telecom line surge suppression.
For engineers reviewing the SMAJ28CAHE3_A/I datasheet, SMAJ28CAHE3_A/I pinout, SMAJ28CAHE3_A/I application, or SMAJ28CAHE3_A/I equivalent, key selection criteria include bidirectional clamping symmetry, AEC-Q101 qualification for automotive use, low thermal resistance (RθJL = 30 °C/W), UL 497B recognition, and compatibility with automated SMT placement on standard PCB pad layouts.
Technical Context
This device operates as a voltage-clamped crowbar during transients: when reverse voltage exceeds VBR, it avalanches to limit downstream voltage to ≤45.4 V at 8.8 A. Its bidirectional structure enables symmetrical clamping in AC-coupled or floating signal paths without polarity sensitivity.
Thermally, it sustains 150 °C junction temperature with 3.3 W steady-state power dissipation and derates linearly above 25 °C ambient; its 120 °C/W junction-to-ambient thermal resistance assumes minimal copper pad area (0.2" × 0.2"), while RθJL = 30 °C/W supports localized heat extraction via leads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before significant leakage; defines safe operating margin below clamping threshold. |
| VBR (min/max) | 31.1 V / 34.4 V at 1 mA - Ensures reliable avalanche initiation across process variation; guarantees clamping starts no later than 34.4 V. |
| VC @ IPPM | 45.4 V at 8.8 A - Limits worst-case transient voltage seen by protected ICs; critical for safeguarding 3.3 V or 5 V logic inputs. |
| PPPM | 400 W (10/1000 μs) - Withstands common lightning-induced surges per IEC 61000-4-5; derates to 300 W above 78 V. |
| IFSM | 40 A (8.3 ms half-sine) - Handles high-energy inrush or fault currents without bond wire fusing. |
| TJ max | 150 °C - Enables operation in under-hood automotive environments and industrial enclosures without forced cooling. |
| MSL Level | Level 1 (J-STD-020) - Supports lead-free reflow up to 260 °C peak without moisture-induced popcorning. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, low-profile plastic case with matte tin-plated leads solderable per J-STD-002. Molding compound meets UL 94 V-0. No polarity marking for bidirectional configuration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry (reverse bias) | One terminal of symmetrical PN junction; conducts during positive or negative overvoltage events relative to cathode. |
| Cathode | Transient current exit (reverse bias) | Second terminal of symmetrical PN junction; completes low-impedance path to ground or rail during clamping. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control modules and ADAS sensor interfaces per stress test requirements. |
| 400 W peak pulse power | Meets IEC 61000-4-5 Level 4 surge immunity (4 kV line-to-earth) when mounted on recommended 5 mm × 5 mm copper pads. |
| Low incremental surge resistance | Minimizes VC overshoot during fast-rising transients (<1 ns rise time), improving protection margin for high-speed interfaces. |
| Glass passivated junction | Enhances long-term reliability and stability of VBR under thermal cycling and humidity exposure. |
| UL 497B recognized (QVGQ2) | Approved for use in telecommunications and industrial safety-critical surge protection circuits per Underwriters Laboratories. |
Applications
| Automotive Sensor Protection | Industrial PLC I/O Protection |
|---|---|
Use Scenario: Protecting CAN bus transceivers and analog sensor inputs (e.g., pressure, temperature) from load dump and ISO 7637-2 pulses in vehicle ECUs. IC Role / Device Role / Timing Role: Bidirectional clamping element placed between signal line and chassis ground to shunt surge energy before reaching sensitive analog front-ends. Use Value: Maintains signal integrity during 100 V/50 ms load dump events by limiting voltage to ≤45.4 V, preventing latch-up or gate oxide damage in downstream ASICs. | Use Scenario: Shielding digital input/output terminals of programmable logic controllers against ESD and inductive switching spikes from solenoids and contactors. IC Role / Device Role / Timing Role: Standoff-and-clamp protector on 24 V DC field wiring, operating continuously at 24 V while responding within <1 ns to transients exceeding 31.1 V. Use Value: Eliminates need for external series impedance or RC filtering, enabling direct connection to microcontroller GPIOs rated for 3.3 V or 5 V logic levels. |
| Telecom Line Interface | Consumer Power Adapter Output |
Use Scenario: Safeguarding Ethernet PHYs and DSL line drivers against lightning-induced surges on twisted-pair data lines per GR-1089-CORE. IC Role / Device Role / Timing Role: Primary-level TVS placed differential-mode across pairs, leveraging bidirectional symmetry to handle both polarities of induced common-mode transients. Use Value: Achieves >20 kV ESD contact discharge immunity and 4 kV surge withstand without degrading 100 MHz signal integrity due to low junction capacitance (~200 pF at 0 V). | Use Scenario: Secondary-side overvoltage clamp on 5 V/9 V/12 V USB-C and wall adapter outputs to prevent damage during regulator failure or cable short-circuits. IC Role / Device Role / Timing Role: Fast-acting crowbar that activates within nanoseconds upon output overvoltage, diverting current away from connected devices until upstream OVP triggers. Use Value: Complies with UL 62368-1 secondary circuit protection requirements while supporting compact board layout due to SMA footprint and RoHS-compliant HE3 suffix. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28CAHM3_A/I | Halogen-free, RoHS-compliant variant with identical electrical specs and AEC-Q101 qualification; same thermal and clamping performance. | No functional difference; selected where halogen-free material compliance is mandated by OEM environmental policy. | Choose SMAJ28CAHM3_A/I when halogen-free bill-of-materials is required; otherwise SMAJ28CAHE3_A/I offers standard RoHS compliance. |
| SMCJ28CAHE3_A/I | Same VWM/VBR/VC but in larger SMC (DO-214AB) package; 1500 W PPPM, lower RθJA (65 °C/W), higher IPPM (37.9 A). | Suitable for higher-energy surge environments (e.g., AC mains input, outdoor equipment); requires larger PCB real estate and different pad layout. | Select SMCJ28CAHE3_A/I only when system-level surge testing exceeds 400 W capability; SMAJ28CAHE3_A/I remains optimal for space-constrained board-level protection. |
Compared with SMAJ28CAHM3_A/I, SMAJ28CAHE3_A/I provides identical protection performance with standard RoHS compliance; versus SMCJ28CAHE3_A/I, it trades higher surge capacity for 40 % smaller footprint and compatibility with fine-pitch automated assembly - ideal for dense automotive and telecom PCBs.
Availability
SMAJ28CAHE3_A/I is available at Aetrix Electronics and suitable for automotive sensor interfaces, industrial PLC I/O protection, and telecom line surge suppression requiring stable component supply, AEC-Q101 qualification, and RoHS compliance.
Supply support for SMAJ28CAHE3_A/I 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 board-level transient suppression in harsh environments - targeting automotive, industrial, and telecom systems where compact size, fast response, and certified qualification are mandatory.
FAQ
What is the clamping voltage of SMAJ28CAHE3_A/I at its rated peak pulse current?
The SMAJ28CAHE3_A/I 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 ensures predictable voltage limiting during surge events. The SMAJ28CAHE3_A/I maintains this clamping performance across its full operating temperature range (-55 °C to +150 °C), making it suitable for under-hood automotive applications where thermal stability is critical.
Is SMAJ28CAHE3_A/I qualified for automotive applications?
Yes, SMAJ28CAHE3_A/I is AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HE3" and documentation in datasheet 88390. This qualification covers stress tests including high-temperature operating life, temperature cycling, and ESD, validating its suitability for automotive subsystems such as body control modules, infotainment interfaces, and ADAS sensor signal conditioning. The SMAJ28CAHE3_A/I meets these requirements while retaining full compatibility with commercial-grade assembly processes.
How does the bidirectional design of SMAJ28CAHE3_A/I affect its circuit implementation?
The bidirectional design of SMAJ28CAHE3_A/I eliminates polarity concerns during placement - there is no cathode band marking, and the device clamps symmetrically for both positive and negative transients. This allows direct integration into AC-coupled lines, differential buses like CAN or RS-485, and floating sensor outputs without additional diodes or orientation checks. The SMAJ28CAHE3_A/I achieves matched VBR and VC in both directions, ensuring consistent protection regardless of transient polarity or grounding scheme.
What is the thermal resistance profile of SMAJ28CAHE3_A/I, and how does it impact PCB layout?
SMAJ28CAHE3_A/I has a typical junction-to-lead thermal resistance (RθJL) of 30 °C/W and junction-to-ambient (RθJA) of 120 °C/W when mounted on 0.2" × 0.2" copper pads. This means effective heat removal relies heavily on copper pour connected to both terminals; increasing pad area or adding thermal vias reduces RθJA significantly. For sustained power dissipation near 3.3 W, the SMAJ28CAHE3_A/I requires careful thermal design - unlike unidirectional variants, its bidirectional structure distributes heat evenly across both leads, supporting balanced thermal loading in compact layouts.
Does SMAJ28CAHE3_A/I meet any safety certification standards?
Yes, SMAJ28CAHE3_A/I is Underwriters Laboratory (UL) recognized under standard UL 497B (file E136766) for protector classification, covering both unidirectional and bidirectional configurations. This certification validates its performance in telecom and industrial surge protection applications, including insulation coordination and failure mode safety. The SMAJ28CAHE3_A/I also complies with RoHS Directive 2011/65/EU and meets JESD201 Class 2 whisker resistance, supporting compliance-driven designs in regulated markets without requiring additional safety agency retesting.
SMAJ28CAHE3_A/I 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:
- -
- Bidirectional Channels:
- 1
- 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ28CAHE3_A/I FAQ
1.How can I place an order for SMAJ28CAHE3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28CAHE3_A/I 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 SMAJ28CAHE3_A/I reliable?
The price and inventory of SMAJ28CAHE3_A/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28CAHE3_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ28CAHE3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28CAHE3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28CAHE3_A/I?
SMAJ28CAHE3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28CAHE3_A/I 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 SMAJ28CAHE3_A/I?
For technical support, including SMAJ28CAHE3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28CAHE3_A/I requirements.
6.How does Aetrix verify that SMAJ28CAHE3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ28CAHE3_A/I 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 SMAJ28CAHE3_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ28CAHE3_A/I?
All SMAJ28CAHE3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28CAHE3_A/I, 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 SMAJ28CAHE3_A/I part is unused and in its original packaging.
Return procedure for SMAJ28CAHE3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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