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Vishay General Semiconductor - Diodes Division SMAJ78AHM3_A/H
- Part No.:
- SMAJ78AHM3_A/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78AHM3_A/H.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:4,294
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Product details
Overview
SMAJ78AHM3_A/H from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients up to 126 V at 3.2 A peak pulse current, with 400 W peak pulse power (10/1000 μs), 78 V stand-off voltage, and 86.7–95.8 V breakdown voltage range - deployed for overvoltage protection of MOSFETs, ICs, and sensor signal lines in automotive power systems.
For engineers reviewing the SMAJ78AHM3_A/H datasheet, SMAJ78AHM3_A/H pinout, SMAJ78AHM3_A/H application, or SMAJ78AHM3_A/H equivalent, this page delivers verified electrical specs, thermal derating behavior, AEC-Q101 qualification status, and precise clamping performance under standardized surge waveforms - critical for ESD and load-dump hardening in 12 V/24 V vehicle subsystems.
Technical Context
The SMAJ78AHM3_A/H operates as a unidirectional avalanche diode, conducting only when reverse voltage exceeds its specified breakdown range (86.7–95.8 V at 1 mA test current), with clamping voltage fixed at ≤126 V under 3.2 A 10/1000 μs surge. Its glass-passivated junction ensures stable leakage (<1.0 μA at 78 V) and fast response time (<1 ns).
Thermally, it features RθJA = 120 °C/W and RθJL = 30 °C/W, enabling operation from –55 °C to +150 °C junction temperature. It meets MSL Level 1 per J-STD-020 and is halogen-free, RoHS-compliant, and AEC-Q101 qualified - confirming suitability for automotive under-hood environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VWM) | 78 V - maximum continuous reverse operating voltage before significant conduction begins |
| Breakdown Voltage (VBR) | 86.7–95.8 V at 1 mA - defines the onset of controlled avalanche clamping |
| Clamping Voltage (VC) | ≤126 V at 3.2 A (10/1000 μs) - peak voltage seen by protected circuit during surge |
| Peak Pulse Power (PPPM) | 400 W (≤78 V); 300 W (>78 V) - surge energy handling capability on standard PCB pads |
| Reverse Leakage (ID) | ≤1.0 μA at 78 V - negligible standby current, preserving low-power system integrity |
| Operating Temperature | –55 °C to +150 °C - validated for under-hood automotive deployment without derating loss |
| AEC-Q101 Qualified | Yes - certified for automotive-grade reliability including temperature cycling, HTRB, and ESD stress |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, low-profile case with matte tin-plated leads solderable per J-STD-002 and JESD 22-B102. Cathode indicated by band marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / reverse surge return path | Connected to ground or low-impedance return in unidirectional TVS configuration |
| Cathode | Avalanche conduction terminal / protected line connection | Connected directly to the line being protected (e.g., 12 V rail, CAN-H, sensor output) |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Handles automotive load-dump surges (ISO 7637-2 Pulse 5a) without failure on standard 5 mm × 5 mm copper pads |
| AEC-Q101 qualification | Validated for automotive under-hood use including temperature cycling, high-temp reverse bias, and mechanical shock |
| Glass passivated junction | Ensures stable VBR tolerance and low leakage drift across lifetime and temperature extremes |
| Halogen-free & RoHS-compliant (HM3 suffix) | Meets automotive environmental compliance requirements and JEDEC JESD201 Class 2 whisker resistance |
| MSL Level 1 (260 °C peak reflow) | Compatible with standard lead-free SMT assembly processes without moisture sensitivity concerns |
Applications
| Automotive Power Rail Protection | Industrial Sensor Signal Line Clamping |
|---|---|
|
Use Scenario: Protecting 12 V/24 V battery-fed ECUs against ISO 7637-2 load-dump transients up to 60 V overshoot. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp surges before they reach downstream regulators and microcontrollers. Use Value: Limits peak rail voltage to ≤126 V during 3.2 A surge, preventing latch-up or gate oxide damage in 40 V-rated MOSFETs and LDOs. |
Use Scenario: Safeguarding analog outputs of pressure/temperature sensors in factory automation PLC modules exposed to relay coil flyback. IC Role / Device Role / Timing Role: TVS connected across sensor output and ground to absorb inductive kickback from nearby solenoid drivers. Use Value: Clamps transients within <1 ns while adding <1 pF capacitance - preserving signal bandwidth up to 1 MHz without distortion. |
| Automotive CAN Transceiver Interface | Consumer Power Adapter Input Stage |
|
Use Scenario: Secondary-level surge suppression on CAN-H/CAN-L lines in body control modules subjected to ESD and coupled noise. IC Role / Device Role / Timing Role: Unidirectional TVS on each CAN line referenced to ground, complementing primary common-mode choke filtering. Use Value: Maintains differential integrity by clamping common-mode spikes to ≤126 V while allowing full CAN FD signaling up to 5 Mbps. |
Use Scenario: Input-stage overvoltage protection in universal AC/DC adapters for smart home devices, guarding against mains surges and lightning-induced spikes. IC Role / Device Role / Timing Role: TVS placed after bridge rectifier and bulk capacitor to clamp DC bus overvoltage events before primary-side controller. Use Value: Absorbs 400 W surges without degradation, enabling compact design with no need for external MOVs or spark gaps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78AHE3_A/H | Same electrical specs; RoHS-compliant but not halogen-free; lacks AEC-Q101 qualification | Acceptable for commercial/industrial use where automotive reliability testing is not required | Select when cost sensitivity outweighs halogen-free or automotive qualification needs |
| SMAJ78A-M3/61 | Identical TVS parameters; same HM3 halogen-free material; differs only in packaging (61 = 7" reel, 1800 pcs) | No functional difference - purely logistics variant for high-volume SMT line feeding | Choose for automated placement compatibility with existing tape-and-reel infrastructure |
Compared with SMAJ78AHM3_A/H, the HE3 variant trades halogen-free construction and AEC-Q101 validation for lower cost in non-automotive settings, while the M3/61 offers identical performance in a different reel format - making SMAJ78AHM3_A/H the optimal choice when both environmental compliance and automotive qualification are mandatory.
Availability
SMAJ78AHM3_A/H is available at Aetrix Electronics and suitable for automotive ECU protection, industrial sensor interface hardening, CAN bus surge suppression, and consumer power adapter input stages requiring stable component supply across production lifecycles.
Supply support for SMAJ78AHM3_A/H 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 and application-specific performance.
The SMAJ series was engineered specifically for robust transient suppression in automotive and industrial power systems, balancing high surge capacity, tight VBR tolerance, and AEC-Q101 compliance in compact surface-mount packages.
FAQ
What is the clamping voltage of SMAJ78AHM3_A/H at its rated peak pulse current?
The SMAJ78AHM3_A/H has a maximum clamping voltage (VC) of 126 V at 3.2 A peak pulse current with a 10/1000 μs waveform. This value is measured under standardized test conditions on 0.2" × 0.2" copper pads and represents the upper voltage limit imposed on the protected circuit during surge events - a key parameter for ensuring downstream ICs remain within absolute maximum ratings. The SMAJ78AHM3_A/H maintains this clamping performance across its full operating temperature range.
Is SMAJ78AHM3_A/H qualified for automotive applications?
Yes, SMAJ78AHM3_A/H is AEC-Q101 qualified, meaning it has passed rigorous stress tests including high-temperature reverse bias (HTRB), temperature cycling, and ESD robustness required for automotive under-hood and chassis-mounted electronics. The "HM3" suffix confirms halogen-free, RoHS-compliant construction and JESD201 Class 2 whisker resistance - all documented in Vishay's official qualification report for the SMAJ78A family. This makes SMAJ78AHM3_A/H suitable for engine control units, body modules, and ADAS power supplies.
How does the breakdown voltage tolerance of SMAJ78AHM3_A/H affect circuit design?
The SMAJ78AHM3_A/H exhibits a guaranteed breakdown voltage (VBR) range of 86.7 V to 95.8 V at 1 mA test current. This ±5% tolerance informs minimum margin between VBR and the protected circuit's absolute maximum voltage rating - for example, a 100 V-rated MOSFET requires ≥4 V headroom above VBR max. Designers must verify that worst-case VBR (95.8 V) still allows safe clamping below the device's breakdown threshold, especially under elevated temperature where VBR increases slightly (0.106 %/°C tempco).
Can SMAJ78AHM3_A/H be used in bidirectional configurations?
No, SMAJ78AHM3_A/H is a unidirectional TVS diode, indicated by the "A" suffix and cathode band marking. It conducts only in reverse bias and blocks forward current beyond ~3.5 V. For bidirectional protection (e.g., AC lines or differential buses), the SMAJ78CA variant must be used instead. Attempting to use SMAJ78AHM3_A/H in bidirectional roles risks forward conduction during normal operation and failure to suppress positive-going transients on grounded lines.
What is the thermal resistance and how does it impact PCB layout for SMAJ78AHM3_A/H?
SMAJ78AHM3_A/H has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W and junction-to-lead (RθJL) of 30 °C/W. To maintain safe operation at full 400 W surge rating, the device must be mounted on minimum recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. Reducing pad area increases junction temperature rise - e.g., halving pad size may raise RθJA by >30%, risking thermal runaway during repetitive surges. Layout must also avoid thermal isolation from ground planes.
SMAJ78AHM3_A/H 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):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 3.2A
- 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)
SMAJ78AHM3_A/H FAQ
1.How can I place an order for SMAJ78AHM3_A/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78AHM3_A/H 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 SMAJ78AHM3_A/H reliable?
The price and inventory of SMAJ78AHM3_A/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78AHM3_A/H is usually 5 days.
3.What payment methods are accepted for SMAJ78AHM3_A/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78AHM3_A/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78AHM3_A/H?
SMAJ78AHM3_A/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78AHM3_A/H 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 SMAJ78AHM3_A/H?
For technical support, including SMAJ78AHM3_A/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78AHM3_A/H requirements.
6.How does Aetrix verify that SMAJ78AHM3_A/H is sourced from the original manufacturer or authorized distributors?
All SMAJ78AHM3_A/H 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 SMAJ78AHM3_A/H meets industry standards.
7.What is the process for return or replacement of SMAJ78AHM3_A/H?
All SMAJ78AHM3_A/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78AHM3_A/H, 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 SMAJ78AHM3_A/H part is unused and in its original packaging.
Return procedure for SMAJ78AHM3_A/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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