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Vishay General Semiconductor - Diodes Division SMAJ28CAHM3/I
- Part No.:
- SMAJ28CAHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28CAHM3/I.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,191
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Product details
Overview
SMAJ28CAHM3/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 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 sensor interfaces, industrial I/O modules, and telecom line protection.
For engineers reviewing the SMAJ28CAHM3/I datasheet, SMAJ28CAHM3/I pinout, SMAJ28CAHM3/I application, or SMAJ28CAHM3/I equivalent, this device serves as a halogen-free, AEC-Q101 qualified TVS for bidirectional surge suppression where low clamping voltage, fast response (<1 ps), and MSL Level 1 reflow compatibility are critical design requirements.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, with identical electrical characteristics in forward and reverse directions. Its glass-passivated junction ensures stable breakdown behavior and low leakage (<1 μA at VWM), while the DO-214AC package supports automated SMT placement and meets UL 94 V-0 flammability rating.
The device delivers 400 W peak pulse power up to 78 V (derated to 300 W above 78 V), with thermal resistance of 120 °C/W (junction-to-ambient) and 30 °C/W (junction-to-lead). It is rated for operating junction temperatures from –55 °C to +150 °C and qualified per AEC-Q101 for automotive under-hood applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM (Stand-off Voltage) | 28 V - Maximum continuous reverse working voltage before clamping begins; defines safe operating margin below breakdown. |
| VBR (Breakdown Voltage) | 31.1–34.4 V at 1 mA - Confirmed breakdown threshold range; ensures reliable triggering during transients without premature conduction. |
| VC (Clamping Voltage) | 45.4 V at 8.8 A IPPM - Peak voltage seen by protected circuit during 10/1000 μs surge; determines stress on downstream components. |
| PPPM (Peak Pulse Power) | 400 W (10/1000 μs) - Energy-handling capability for single transient events; sufficient for ISO 7637-2 Pulse 1/2a/5a and IEC 61000-4-5 surges. |
| IPPM (Peak Pulse Current) | 8.8 A - Maximum surge current the device safely shunts; derived from VC and PPPM, critical for PCB trace sizing. |
| TJmax | +150 °C - Maximum junction temperature; enables operation in high-ambient environments like engine control units or power supplies. |
| Package | SMA (DO-214AC) - Standard surface-mount outline with 5.28 mm × 4.50 mm footprint; compatible with JEDEC MS-013 and IPC-7351B. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; bidirectional configuration with no polarity marking (unlike unidirectional variants which feature cathode band).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Transient current path (bidirectional) | Both terminals function identically; surge current flows either direction through the same junction - no orientation required during placement. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control, body electronics, and ADAS sensors - supports long-term reliability under thermal cycling and vibration. |
| Halogen-free & RoHS-compliant (HM3 suffix) | Meets IEC 61249-2-21 and JEDEC J-STD-203; eliminates brominated flame retardants without compromising UL 94 V-0 rating or solderability. |
| MSL Level 1 (260 °C peak) | Enables single-reflow assembly without moisture sensitivity concerns - no baking required prior to SMT processing. |
| Low incremental surge resistance | Minimizes VC overshoot during fast-rising transients (e.g., ESD, lightning-induced surges), improving protection margin for 3.3 V/5 V logic interfaces. |
Applications
| Automotive Sensor Interface | Industrial PLC Analog Input |
|---|---|
|
Use Scenario: Protecting CAN/LIN bus transceivers and analog sensor front-ends (e.g., pressure, temperature) from load dump and inductive switching transients in 12 V vehicle systems. IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed directly at connector entry point to limit transient energy before it reaches precision amplifier or microcontroller input pins. Use Value: Clamps 45.4 V at 8.8 A, ensuring downstream 5 V tolerant ICs remain within absolute maximum ratings during ISO 7637-2 Pulse 5a (75 V/100 ms) events. |
Use Scenario: Safeguarding 4–20 mA current loop inputs and ±10 V analog inputs in programmable logic controllers against field wiring surges and ground bounce. IC Role / Device Role / Timing Role: Primary overvoltage protection element mounted adjacent to terminal block, shunting induced transients before signal conditioning circuitry. Use Value: 400 W pulse rating handles repetitive 1 kV/500 A surges per IEC 61000-4-5 (10/1000 μs), maintaining signal integrity without degradation after multiple events. |
| Telecom Line Protection | Consumer USB Port ESD Suppression |
|
Use Scenario: Shielding Ethernet PHY interfaces, RS-485 transceivers, and DSL line drivers from lightning-induced surges and AC power cross-talk in outdoor equipment. IC Role / Device Role / Timing Role: Secondary-level TVS used in conjunction with gas discharge tubes (GDTs) to provide low-clamp backup protection after primary coarse suppression. Use Value: Symmetrical bidirectional response ensures equal protection on differential pairs; 45.4 V clamping prevents latch-up in 3.3 V PHYs during common-mode transients. |
Use Scenario: Adding robustness to USB 2.0 data lines (D+/D−) and VBUS in smart home hubs and portable chargers exposed to human-body-model (HBM) and IEC 61000-4-2 contact ESD. IC Role / Device Role / Timing Role: Fast-response TVS placed immediately after USB connector to divert >8 kV ESD strikes before reaching USB controller or PMIC. Use Value: Sub-nanosecond response time and <1 μA leakage at 28 V ensure no signal distortion or standby current penalty - validated per AEC-Q101 for extended lifecycle. |
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/I | RoHS-compliant but not halogen-free; lacks JESD201 Class 2 whisker resistance certification. | Suitable for commercial-grade industrial controls where halogen-free requirement is absent. | Select when cost sensitivity outweighs automotive or green-material compliance needs. |
| SMBJ28CAHM3/I | Same VWM/VC, but SMB (DO-214AA) package - 20 % larger footprint and 600 W PPPM rating. | Better suited for higher-energy surges (e.g., AC mains coupling) where board space permits larger package. | Choose when system-level surge testing exceeds 400 W and layout allows SMB footprint. |
Compared with SMAJ28CAHM3/I, SMAJ28CAHE3/I offers identical electrical performance but reduced environmental compliance, while SMBJ28CAHM3/I provides higher power handling at the expense of PCB area - making SMAJ28CAHM3/I optimal for space-constrained, AEC-Q101–required automotive and industrial edge nodes.
Availability
SMAJ28CAHM3/I is available at Aetrix Electronics and suitable for automotive sensor protection, industrial I/O conditioning, and telecom line safeguarding requiring stable component supply across multi-year production cycles.
Supply support for SMAJ28CAHM3/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, MOSFETs, optoelectronics, and passive components with emphasis on reliability and application-specific optimization.
The SMAJ series was engineered for high-reliability transient suppression in harsh environments - targeting automotive, industrial automation, and infrastructure applications where AEC-Q101 qualification and consistent clamping performance are mandatory.
FAQ
What is the clamping voltage of SMAJ28CAHM3/I at its rated peak pulse current?
The SMAJ28CAHM3/I has a maximum clamping voltage (VC) of 45.4 V at 8.8 A peak pulse current (IPPM) under the standard 10/1000 μs waveform. This value is measured per ANSI/IEEE C62.35 and defines the upper voltage limit imposed on protected circuits during surge events - critical for ensuring downstream 5 V or 3.3 V ICs remain within safe operating limits. The SMAJ28CAHM3/I maintains this clamping performance across its full operating temperature range (–55 °C to +150 °C).
Is SMAJ28CAHM3/I suitable for automotive applications?
Yes, SMAJ28CAHM3/I is AEC-Q101 qualified and specifically designed for automotive use cases including engine control units, body electronics, and ADAS sensor interfaces. Its halogen-free (HM3) construction, MSL Level 1 reflow compatibility, and guaranteed operation from –55 °C to +150 °C meet stringent automotive reliability requirements. The SMAJ28CAHM3/I is referenced in Vishay's automotive ordering codes and tested per stress test conditions defined in AEC-Q101 Rev D.
How does the bidirectional configuration of SMAJ28CAHM3/I affect PCB layout?
The SMAJ28CAHM3/I has no polarity marking and functions identically in both directions, eliminating orientation constraints during PCB placement. Unlike unidirectional TVS diodes that require cathode alignment, the SMAJ28CAHM3/I can be mounted in either direction across differential lines or ungrounded signal paths - simplifying layout, reducing assembly errors, and enabling symmetric protection on balanced interfaces such as RS-485 or CAN. Its DO-214AC footprint remains unchanged from unidirectional variants.
What is the maximum leakage current of SMAJ28CAHM3/I at its stand-off voltage?
The SMAJ28CAHM3/I exhibits a maximum reverse leakage current (ID) of 1.0 μA at its 28 V stand-off voltage (VWM) and 25 °C ambient temperature. This ultra-low leakage ensures minimal impact on high-impedance sensor circuits and battery-powered systems, preserving signal accuracy and extending standby runtime. Leakage remains below 5 μA up to +85 °C, supporting stable operation in industrial and automotive environments.
Does SMAJ28CAHM3/I require derating above 25 °C ambient temperature?
Yes, SMAJ28CAHM3/I must be derated above 25 °C ambient per Figure 2 in Vishay document 88390. Its peak pulse power rating decreases linearly from 400 W at 25 °C to zero at approximately 150 °C junction temperature. At 75 °C ambient (assuming typical RθJA = 120 °C/W), usable PPPM drops to ~280 W. Designers must calculate actual junction temperature rise using power dissipation, thermal pad layout, and airflow to ensure safe operation - especially in enclosed automotive or industrial enclosures.
SMAJ28CAHM3/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:
- Discontinued at Digi-Key
- 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/I FAQ
1.How can I place an order for SMAJ28CAHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28CAHM3/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/I reliable?
The price and inventory of SMAJ28CAHM3/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/I is usually 5 days.
3.What payment methods are accepted for SMAJ28CAHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28CAHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28CAHM3/I?
SMAJ28CAHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28CAHM3/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/I?
For technical support, including SMAJ28CAHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28CAHM3/I requirements.
6.How does Aetrix verify that SMAJ28CAHM3/I is sourced from the original manufacturer or authorized distributors?
All SMAJ28CAHM3/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/I meets industry standards.
7.What is the process for return or replacement of SMAJ28CAHM3/I?
All SMAJ28CAHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28CAHM3/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/I part is unused and in its original packaging.
Return procedure for SMAJ28CAHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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