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Vishay General Semiconductor - Diodes Division SMAJ28AHM3_A/I
- Part No.:
- SMAJ28AHM3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28AHM3_A/I.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,149
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Product details
Overview
SMAJ28AHM3_A/I from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection of sensitive electronics. 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 (IPPM), and 400 W peak pulse power (10/1000 μs waveform), commonly deployed on DC power rails and I/O lines in automotive ECUs and industrial controllers.
For engineers reviewing the SMAJ28AHM3_A/I datasheet, SMAJ28AHM3_A/I pinout, SMAJ28AHM3_A/I application, or SMAJ28AHM3_A/I equivalent, key selection criteria include its AEC-Q101 qualification (HM3 suffix), halogen-free RoHS compliance, 150 °C max junction temperature, low incremental surge resistance, and compatibility with automated SMT placement on 0.2" × 0.2" copper pads.
Technical Context
This unidirectional TVS diode operates as a voltage-clamping device that remains high-impedance below VWM (28 V) and rapidly transitions to low-impedance conduction above VBR (min 31.1 V) to shunt transient energy. Its glass-passivated junction ensures stable leakage performance and fast response time (<1 ns), critical for protecting MOSFET gates and microcontroller I/O pins against ESD and inductive switching spikes.
The device is rated for 40 A non-repetitive forward surge current (IFSM, 8.3 ms half-sine), supports continuous power dissipation of 3.3 W at 50 °C ambient, and exhibits a thermal resistance of 120 °C/W (junction-to-ambient) when mounted per recommended pad layout - enabling reliable operation in thermally constrained automotive under-hood environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before clamping begins; defines safe DC rail margin for 24 V systems. |
| VBR (min/max) | 31.1 V / 34.4 V at 1 mA - Confirmed breakdown range ensures predictable turn-on across temperature and process variation. |
| VC @ IPPM | 45.4 V at 8.8 A - Clamping voltage during 10/1000 μs transient; limits downstream voltage stress to <46 V during surge events. |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - Peak pulse power rating determines survivability against ISO 7637-2 Pulse 1/2a/5a transients. |
| ID @ VWM | 1.0 μA - Reverse leakage at 28 V; negligible power loss and signal integrity impact in always-on monitoring circuits. |
| TJ max. | +150 °C - Enables use in under-hood automotive applications without derating in high-ambient conditions. |
| Package | SMA (DO-214AC) - Surface-mount package with 0.208" × 0.157" footprint; compatible with standard reflow profiles and J-STD-020 MSL level 1. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; polarity indicated by cathode band on unidirectional devices.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal during clamping | Connected to protected line (e.g., 24 V rail); conducts surge current toward ground when V > VBR. |
| Cathode | Current exit terminal during clamping | Connected to system ground; forms low-impedance path to divert transients away from ICs and sensors. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified (HM3 suffix) | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - suitable for engine control, ADAS, and body electronics. |
| Halogen-free & RoHS-compliant | Meets environmental compliance requirements for global automotive and industrial OEMs without compromising surge robustness. |
| 400 W peak pulse power (10/1000 μs) | Withstands high-energy transients such as load dump (ISO 16750-2) and inductive kickback in 24 V systems. |
| Low clamping ratio (VC/VBR ≈ 1.45) | Minimizes voltage overshoot during clamping - protects 3.3 V/5 V logic interfaces even when placed downstream of LDOs. |
| MSL level 1, peak reflow ≤260 °C | Enables single-pass lead-free reflow assembly without moisture sensitivity concerns or baking requirements. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 24 V supply inputs of engine control units (ECUs) against ISO 7637-2 Pulse 1 (inductive switch-off) and Pulse 5a (load dump). IC Role / Device Role / Timing Role: Unidirectional clamping TVS placed between battery rail and input filter capacitor, acting as first-line transient shunt. Use Value: Limits voltage excursion to ≤45.4 V during 8.8 A surges, preventing damage to upstream DC-DC converters and MCU power domains. |
Use Scenario: Safeguarding analog output lines (e.g., 4–20 mA current loops) of pressure/temperature sensors in factory automation PLCs. IC Role / Device Role / Timing Role: Bidirectional-capable but used unidirectionally across sensor supply and return paths to clamp reverse polarity and ESD events. Use Value: Sub-1 μA leakage at 28 V avoids loading precision current sources; fast response preserves signal fidelity during transient coupling. |
| Telecom DC Power Input Protection | Consumer Device USB Port Protection |
|
Use Scenario: Securing 24–48 V DC inputs of PoE-powered network switches and base station radios against lightning-induced surges. IC Role / Device Role / Timing Role: Primary TVS on main DC input, coordinated with upstream fuses and secondary filtering to meet IEC 61000-4-5 Level 3. Use Value: 400 W rating enables handling of 10/1000 μs surges up to 8.8 A without degradation - extends field life in outdoor telecom enclosures. |
Use Scenario: Adding overvoltage resilience to USB-C VBUS lines in portable medical monitors and smart home hubs powered via 24 V adapters. IC Role / Device Role / Timing Role: Secondary-level TVS after primary fuse and common-mode choke, clamping fast-rising transients from adapter faults or hot-plug events. Use Value: 150 °C TJ max and MSL level 1 support compact, sealed designs with no thermal derating needed in confined PCB layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28AHE3_A/I | Same electrical specs, but RoHS-compliant commercial grade (E3) without halogen-free certification or AEC-Q101 qualification. | Lacks automotive qualification and halogen-free compliance - suitable only for non-automotive industrial or consumer applications. | Select SMAJ28AHE3_A/I when AEC-Q101 and halogen-free requirements are not mandated, reducing cost where full automotive spec is unnecessary. |
| SMBJ28A-HM3_A/I | Same VWM (28 V), but SMB package (DO-214AA) with higher 600 W PPPM rating and 12.5 A IPPM; larger footprint and higher thermal mass. | Better suited for higher-energy transients (e.g., ISO 16750-2 Pulse 5b); requires larger PCB area and different pad layout. | Choose SMBJ28A-HM3_A/I when system-level surge testing exceeds 400 W capability or when design margin demands lower clamping voltage under higher current. |
Compared with SMAJ28AHM3_A/I, SMAJ28AHE3_A/I offers identical clamping performance without automotive qualification, while SMBJ28A-HM3_A/I provides higher surge capacity at the cost of increased board space - enabling tiered selection based on environmental rigor and transient severity.
Availability
SMAJ28AHM3_A/I is available at Aetrix Electronics and suitable for automotive ECUs, industrial sensor modules, telecom power supplies, and consumer USB-C power delivery systems requiring stable component supply with guaranteed long-term continuity.
Supply support for SMAJ28AHM3_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 validation.
The SMAJ series is engineered for high-reliability transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where consistent clamping performance and AEC-Q101 compliance are mandatory.
FAQ
What is the maximum clamping voltage of SMAJ28AHM3_A/I at its rated peak pulse current?
The SMAJ28AHM3_A/I has a maximum clamping voltage (VC) of 45.4 V at its specified peak pulse current (IPPM) of 8.8 A under a 10/1000 μs waveform. This value is measured per JEDEC standards and ensures downstream components experience no more than 45.4 V during transient events - critical for safeguarding 3.3 V or 5 V logic interfaces fed from 24 V rails. The clamping behavior is repeatable and validated across temperature and production lots.
Is SMAJ28AHM3_A/I suitable for automotive applications?
Yes, SMAJ28AHM3_A/I is explicitly qualified to AEC-Q101 and carries the HM3 suffix denoting halogen-free, RoHS-compliant, and automotive-grade construction. It meets requirements for temperature cycling, high-temperature reverse bias, and ESD robustness - making it appropriate for engine control units, body control modules, and ADAS sensors where sustained operation up to +150 °C and immunity to ISO 7637-2 transients are required.
How does the SMAJ28AHM3_A/I differ from SMAJ28AHE3_A/I?
SMAJ28AHM3_A/I and SMAJ28AHE3_A/I share identical electrical parameters (VWM = 28 V, VC = 45.4 V, PPPM = 400 W), but differ in qualification and material compliance: HM3 denotes halogen-free + AEC-Q101, while HE3 indicates RoHS-compliant commercial grade only. SMAJ28AHM3_A/I is certified for automotive use; SMAJ28AHE3_A/I is restricted to non-automotive applications where halogen-free and AEC-Q101 are not mandated.
What is the thermal resistance of SMAJ28AHM3_A/I, and how does it affect PCB layout?
SMAJ28AHM3_A/I has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on the minimum recommended 0.2" × 0.2" copper pads per terminal. This value assumes standard FR-4 PCB with no internal planes - so designers must allocate adequate copper area and avoid excessive trace length to maintain junction temperature below 150 °C during repetitive surge events. Thermal derating curves in the datasheet guide layout adjustments for elevated ambient temperatures.
Does SMAJ28AHM3_A/I support automated SMT assembly?
Yes, SMAJ28AHM3_A/I is optimized for automated surface-mount assembly: it uses matte tin-plated leads compliant with J-STD-002 and JESD 22-B102, meets MSL level 1 per J-STD-020 (peak reflow ≤260 °C), and features a low-profile SMA (DO-214AC) package compatible with standard pick-and-place and reflow processes. No baking or special handling is required prior to assembly.
SMAJ28AHM3_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:
- 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:
- 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)
SMAJ28AHM3_A/I FAQ
1.How can I place an order for SMAJ28AHM3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28AHM3_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 SMAJ28AHM3_A/I reliable?
The price and inventory of SMAJ28AHM3_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 SMAJ28AHM3_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ28AHM3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28AHM3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28AHM3_A/I?
SMAJ28AHM3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28AHM3_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 SMAJ28AHM3_A/I?
For technical support, including SMAJ28AHM3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28AHM3_A/I requirements.
6.How does Aetrix verify that SMAJ28AHM3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ28AHM3_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 SMAJ28AHM3_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ28AHM3_A/I?
All SMAJ28AHM3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28AHM3_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 SMAJ28AHM3_A/I part is unused and in its original packaging.
Return procedure for SMAJ28AHM3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ28AHM3_A/I Tags
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