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Vishay General Semiconductor - Diodes Division SMAJ28CAHM3_A/I
- Part No.:
- SMAJ28CAHM3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28CAHM3_A/I.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SMAJ28CAHM3_A/I from Vishay General Semiconductor is a bidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on signal or power lines. It features 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 - used to protect MOSFETs, ICs, and sensor interfaces in automotive and industrial control systems.
For engineers reviewing the SMAJ28CAHM3_A/I datasheet, SMAJ28CAHM3_A/I pinout, SMAJ28CAHM3_A/I application, or SMAJ28CAHM3_A/I equivalent, this device delivers verified bidirectional surge suppression with AEC-Q101 qualification, halogen-free RoHS compliance, and MSL Level 1 moisture sensitivity - critical for high-reliability embedded power rail and communication line protection.
Technical Context
This TVS diode operates symmetrically in both directions due to its bidirectional CA construction, enabling transient suppression without polarity constraints on AC-coupled or differential signal paths. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1.0 μA at VWM), while the low incremental surge resistance supports fast energy dissipation during ESD or lightning-induced surges.
The device is rated for -55 °C to +150 °C operating junction temperature and exhibits a typical thermal resistance of 120 °C/W (junction-to-ambient) on standard 0.2" × 0.2" copper pads. Its 10/1000 μs waveform response is validated per ANSI/IEEE C62.35, with derating applied above 25 °C ambient per Figure 2 in the datasheet.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse working voltage before clamping begins; defines safe operating margin for 24 V nominal systems. |
| VBR min/max | 31.1 V / 34.4 V at 1 mA - Confirmed breakdown range ensures reliable turn-on within specification across production lot. |
| VC @ IPPM | 45.4 V at 8.8 A - Clamping voltage under full 400 W surge; limits downstream voltage stress to ≤45.4 V during transient events. |
| PPPM | 400 W (10/1000 μs) - Peak pulse power handling capacity; sufficient for IEC 61000-4-5 Level 3 (1 kV/2 Ω) surge testing. |
| IPPM | 8.8 A - Peak pulse current capability derived from PPPM/VC; enables robust protection against repetitive switching transients. |
| TJ max | +150 °C - Maximum junction temperature rating; supports operation in under-hood automotive environments and sealed industrial enclosures. |
| Package | SMA (DO-214AC) - Standardized surface-mount outline with 5.28 mm length, 4.50 mm width, and 2.29 mm height; compatible with automated pick-and-place. |
Pinout & Package
Package: SMA (DO-214AC), bidirectional configuration - no polarity marking; symmetrical two-terminal construction with cathode/anode interchangeable in circuit layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Terminal 1 | Anode / Cathode (bidirectional) | Either terminal serves as anode or cathode depending on instantaneous polarity; no fixed polarity required in PCB layout. |
| Terminal 2 | Anode / Cathode (bidirectional) | Complementary terminal completing the symmetrical TVS path; enables clamping on both positive and negative excursions. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - suitable for engine control, ADAS, and body electronics. |
| Halogen-free & RoHS-compliant | HM3 suffix confirms halogen-free molding compound and lead-free matte tin plating - meets IPC-J-STD-020 and JESD22-B102 solderability standards. |
| 400 W peak pulse power | Rated for 10/1000 μs waveform with 0.01% duty cycle - provides margin for repeated inductive load switching in motor drives and solenoid controls. |
| Low clamping ratio (VC/VBR ≈ 1.37) | Clamps at only 1.37× minimum breakdown voltage - minimizes overvoltage exposure to protected ICs compared to higher-ratio suppressors. |
| MSL Level 1 | Moisture sensitivity level 1 per J-STD-020 - allows unlimited floor life and reflow at peak 260 °C without baking preconditioning. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Suppressing load dump and alternator ripple transients on 24 V battery-fed ECUs in commercial vehicles. IC Role / Device Role / Timing Role: Bidirectional TVS placed across power input pins to clamp ±100 V spikes to <45.4 V within nanoseconds. Use Value: Prevents latch-up or gate oxide damage in MCU power management ICs by limiting transient overvoltage below absolute maximum ratings. |
Use Scenario: Protecting analog front-end inputs of pressure/temperature sensors connected to long harnesses in factory automation. IC Role / Device Role / Timing Role: Placed differential-mode across sensor signal pair (e.g., RS-485 A/B) to absorb EFT bursts and cable discharge events. Use Value: Maintains signal integrity by clamping common-mode surges before they couple into precision ADC reference paths or op-amp inputs. |
| Telecom Line Surge Protection | Consumer USB Port ESD Protection |
|
Use Scenario: Guarding Ethernet PHY interface lines (e.g., MDI-X pairs) against induced lightning surges in outdoor access points. IC Role / Device Role / Timing Role: Used in conjunction with common-mode chokes to shunt differential-mode surges to ground before reaching magnetics. Use Value: Enables compliance with IEC 61000-4-5 (10/700 μs) with <10 ns response time - avoids data corruption or PHY reset during field deployment. |
Use Scenario: Safeguarding USB 2.0 D+/D− lines in smart home hubs against human-body-model (HBM) ESD events up to ±15 kV. IC Role / Device Role / Timing Role: Mounted directly at connector with minimal trace length to minimize inductance and ensure sub-1 ns response. Use Value: Limits ESD-induced voltage on transceiver pins to <45.4 V - prevents permanent damage to USB PHY silicon while maintaining signal rise/fall times. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28CAHE3_A/I | Same electrical specs but RoHS-compliant (non-halogen-free) construction; lacks halogen-free certification. | Acceptable for commercial/industrial use where halogen-free requirement is not mandated by end-customer spec. | Select when cost sensitivity outweighs halogen-free compliance; identical footprint and performance in non-automotive designs. |
| SMBJ28CAHM3_A/I | Higher 600 W peak pulse power rating; larger SMB (DO-214AA) package (5.28 mm × 4.57 mm vs. 5.28 mm × 4.50 mm). | Better suited for higher-energy transients (e.g., IEC 61000-4-5 Level 4); requires PCB pad revision due to wider body. | Choose when system-level surge testing exceeds 400 W margin; verify thermal relief and board space accommodate 0.07 mm wider body. |
Compared with SMAJ28CAHE3_A/I, the SMAJ28CAHM3_A/I adds halogen-free compliance for automotive Tier 1 supply chains; versus SMBJ28CAHM3_A/I, it trades 50% lower pulse power for smaller footprint and lower parasitic inductance - optimizing for space-constrained 24 V control modules.
Availability
SMAJ28CAHM3_A/I is available at Aetrix Electronics and suitable for automotive power rail protection, industrial sensor interface hardening, telecom line surge suppression, and consumer USB port ESD protection requiring stable component supply across multi-year production cycles.
Supply support for SMAJ28CAHM3_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, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.
The SMAJ series is engineered for high-speed transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where AEC-Q101 qualification, low clamping voltage, and repeatable surge endurance are mandatory.
FAQ
What is the maximum clamping voltage of the SMAJ28CAHM3_A/I under a 10/1000 μs surge?
The SMAJ28CAHM3_A/I has a maximum clamping voltage (VC) of 45.4 V at 8.8 A peak pulse current, measured under the standardized 10/1000 μs waveform. This value is guaranteed across the full operating temperature range and represents the upper limit of voltage imposed on protected circuitry during surge events - critical for ensuring downstream ICs remain within their absolute maximum ratings. The SMAJ28CAHM3_A/I achieves this with low incremental resistance and symmetrical bidirectional conduction.
Is the SMAJ28CAHM3_A/I suitable for automotive applications?
Yes, the SMAJ28CAHM3_A/I is AEC-Q101 qualified and carries the HM3 suffix indicating halogen-free, RoHS-compliant construction - meeting stringent automotive reliability requirements for under-hood and chassis-mounted electronics. It is explicitly listed in Vishay's AEC-Q101 qualified product table with validation for temperature cycling, high-temperature reverse bias, and ESD robustness. The SMAJ28CAHM3_A/I is deployed in engine control units, body control modules, and ADAS camera power supplies where transient immunity is mission-critical.
How does the bidirectional design of the SMAJ28CAHM3_A/I affect its circuit placement?
The SMAJ28CAHM3_A/I is inherently bidirectional (denoted by "CA") and features no polarity marking - both terminals are functionally identical and interchangeable. This eliminates orientation constraints during PCB layout and allows direct placement across AC-coupled lines, differential pairs (e.g., RS-485), or ungrounded power rails without concern for anode/cathode alignment. Unlike unidirectional variants, the SMAJ28CAHM3_A/I clamps equally on positive and negative voltage excursions, simplifying design for systems subject to bipolar transients.
What is the thermal resistance of the SMAJ28CAHM3_A/I, and how does it impact PCB layout?
The SMAJ28CAHM3_A/I has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal - as specified in the Vishay datasheet. This value assumes minimal copper area; increasing pad size or adding thermal vias reduces RθJA and improves surge endurance. For sustained surge duty cycles or high ambient temperatures, designers should verify junction temperature using PD = 3.3 W and derating curves in Figure 2 to avoid exceeding the +150 °C TJ max. The SMAJ28CAHM3_A/I's thermal performance directly influences layout decisions for automotive and industrial deployments.
Does the SMAJ28CAHM3_A/I require special handling or moisture precautions before reflow?
No - the SMAJ28CAHM3_A/I is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life and may be subjected to standard lead-free reflow profiles with peak temperatures up to 260 °C without prior baking. This eliminates moisture sensitivity concerns during manufacturing and supports just-in-time assembly. The device's DO-214AC package and matte tin-plated leads comply with J-STD-002 and JESD22-B102 for solderability, ensuring robust joint formation. The SMAJ28CAHM3_A/I is optimized for high-yield SMT processes in volume production environments.
SMAJ28CAHM3_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:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ28CAHM3_A/I FAQ
1.How can I place an order for SMAJ28CAHM3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28CAHM3_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 SMAJ28CAHM3_A/I reliable?
The price and inventory of SMAJ28CAHM3_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 SMAJ28CAHM3_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ28CAHM3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28CAHM3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28CAHM3_A/I?
SMAJ28CAHM3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28CAHM3_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 SMAJ28CAHM3_A/I?
For technical support, including SMAJ28CAHM3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28CAHM3_A/I requirements.
6.How does Aetrix verify that SMAJ28CAHM3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ28CAHM3_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 SMAJ28CAHM3_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ28CAHM3_A/I?
All SMAJ28CAHM3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28CAHM3_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 SMAJ28CAHM3_A/I part is unused and in its original packaging.
Return procedure for SMAJ28CAHM3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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