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Vishay General Semiconductor - Diodes Division SMAJ78AHM3/H
- Part No.:
- SMAJ78AHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78AHM3/H.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,677
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Product details
Overview
SMAJ78AHM3/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 on power and signal lines. It features a 78 V stand-off voltage (VWM), 86.7–95.8 V breakdown voltage (VBR) at 1 mA, 126 V maximum clamping voltage (VC) at 3.2 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 industrial power supplies and automotive control modules.
For engineers reviewing the SMAJ78AHM3/H datasheet, SMAJ78AHM3/H pinout, SMAJ78AHM3/H application, or SMAJ78AHM3/H equivalent, key selection criteria include its 78 V working voltage, 126 V clamping performance under 3.2 A surge, AEC-Q101 qualification (HM3 suffix), halogen-free RoHS compliance, and suitability for board-level ESD and lightning surge protection in DC power rails and low-speed data lines.
Technical Context
This TVS diode operates as a unidirectional avalanche clamp, activated when reverse voltage exceeds its 86.7–95.8 V breakdown range. Its glass-passivated junction ensures stable leakage (<1.0 μA at 78 V) and fast response time (<1.0 ps), enabling effective suppression of inductive switching spikes and EFT bursts.
Thermally, it exhibits 120 °C/W junction-to-ambient resistance (RθJA) on standard 0.2" × 0.2" copper pads and supports continuous power dissipation of 3.3 W at 50 °C ambient. The HM3 suffix confirms halogen-free, RoHS-compliant construction and AEC-Q101 qualification for automotive-grade reliability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM (Stand-off Voltage) | 78 V - maximum continuous reverse operating voltage before clamping initiates; defines safe DC rail margin for 12 V–48 V systems. |
| VBR (Breakdown Voltage) | 86.7–95.8 V at 1 mA - precise avalanche onset range ensuring predictable turn-on during overvoltage events. |
| VC (Clamping Voltage) | 126 V at IPPM = 3.2 A - peak voltage seen by protected circuit during 10/1000 μs surge; enables robust margin vs. 100 V-rated components. |
| PPPM (Peak Pulse Power) | 400 W (≤78 V), 300 W (>78 V) - surge energy handling capability per JEDEC-standard 10/1000 μs waveform. |
| ID (Reverse Leakage) | ≤1.0 μA at 78 V - negligible standby current draw, critical for low-power sensor and battery-backed circuits. |
| TJ max. | 150 °C - maximum junction temperature supporting operation in under-hood automotive and industrial enclosures. |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline with 5.28 mm length, 4.50 mm width, and 2.29 mm height for automated assembly. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, MSL Level 1 (JEDEC J-STD-020), compatible with lead-free reflow up to 260 °C peak.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Transient current sink node | Connected to protected line; conducts surge current to ground during overvoltage; polarity must be observed for unidirectional operation. |
| Anode | Reference/ground return path | Typically tied to system ground or low-impedance return plane; completes clamping loop with minimal inductance for effective transient suppression. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Enables single-device protection against IEC 61000-4-5 Level 3 (1 kV/2 Ω) surges on 24 V DC rails without derating. |
| AEC-Q101 qualified (HM3 suffix) | Validated for automotive applications including engine control units, body electronics, and ADAS power domains with extended temperature and lifetime requirements. |
| Glass passivated junction | Ensures stable VBR tolerance and low leakage across -55 °C to +150 °C, critical for high-reliability industrial deployments. |
| Halogen-free & RoHS-compliant | Meets EU Directive 2011/65/EU and IPC-1752A material declarations; supports green manufacturing and end-of-life recycling compliance. |
| Low incremental surge resistance | Minimizes clamping voltage overshoot during fast-rising transients (e.g., ISO 7637-2 pulse 1/2a), improving protection margin for downstream ICs. |
Applications
| Automotive Power Rail Protection | Industrial PLC I/O Module Protection |
|---|---|
|
Use Scenario: Suppressing load dump and alternator ripple transients on 24 V battery-fed ECUs. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between power input and ground, triggered within picoseconds of overvoltage onset. Use Value: Limits voltage to ≤126 V during 3.2 A surge, protecting 36 V-rated DC-DC converters and CAN transceivers from permanent damage. |
Use Scenario: Guarding analog input channels of programmable logic controllers against field-wiring induced surges. IC Role / Device Role / Timing Role: Standoff device in series with signal conditioning circuitry, absorbing ±1 kV EFT bursts per IEC 61000-4-4. Use Value: Maintains <1.0 μA leakage at 78 V, preserving 16-bit ADC accuracy while clamping transients before op-amp front-end stages. |
| Telecom DC Power Feeds | Consumer Appliance Motor Drive Protection |
|
Use Scenario: Safeguarding PoE-powered remote units against lightning-induced surges on 48 V DC distribution lines. IC Role / Device Role / Timing Role: Primary clamping element at power entry point, coordinated with upstream GDT or MOV for staged protection. Use Value: Delivers 400 W peak power handling with 120 °C/W thermal resistance, enabling compact layout without heatsinking in sealed enclosures. |
Use Scenario: Protecting microcontroller GPIOs and gate drivers from back-EMF spikes generated by brushed DC motors. IC Role / Device Role / Timing Role: Fast-response shunt suppressor across motor terminals or H-bridge supply rails. Use Value: Clamps 8.3 ms half-sine surges up to 40 A (IFSM), preventing latch-up in 5 V logic and sustaining 150 °C junction temperature during repeated actuation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78AHE3/H | Same electrical specs, but RoHS-compliant (E3) without halogen-free certification; no AEC-Q101 qualification. | Approved for commercial/industrial use only; not rated for automotive under-hood environments. | Select when halogen-free requirement is waived and automotive qualification is unnecessary. |
| SMBJ78A-H | Same VWM/VBR/VC ratings, but SMB (DO-214AA) package - 25 % larger footprint and higher RθJA (150 °C/W). | Lower power density; requires larger PCB area and may need thermal relief for same 400 W surge duty cycle. | Choose only if existing layout uses SMB footprint or higher thermal mass is acceptable. |
Compared with SMAJ78AHM3/H, SMAJ78AHE3/H lacks halogen-free and AEC-Q101 validation, limiting automotive deployment, while SMBJ78A-H trades compactness and thermal efficiency for mechanical compatibility - making SMAJ78AHM3/H optimal for space-constrained, automotive-qualified, and environmentally regulated designs.
Availability
SMAJ78AHM3/H is available at Aetrix Electronics and suitable for automotive control units, industrial PLC I/O modules, telecom DC power feeds, and consumer appliance motor drives requiring stable component supply and long-term lifecycle support.
Supply support for SMAJ78AHM3/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, MOSFETs, and protection devices with emphasis on reliability, precision, and application-specific optimization.
The SMAJ series delivers standardized, high-power TVS protection for DC power and signal lines across automotive, industrial, and telecom markets - engineered for rapid transient response, tight parametric consistency, and robust environmental qualification.
FAQ
What is the clamping voltage of SMAJ78AHM3/H at its rated peak pulse current?
The SMAJ78AHM3/H has a maximum clamping voltage (VC) of 126 V at its specified peak pulse current (IPPM) of 3.2 A, measured under the standard 10/1000 μs waveform. This value ensures protected circuits remain below critical voltage thresholds during surge events, and is confirmed in Vishay's datasheet Document Number 88390, page 2, Electrical Characteristics table for SMAJ78A.
Is SMAJ78AHM3/H qualified for automotive applications?
Yes, SMAJ78AHM3/H is AEC-Q101 qualified, as indicated by the "HM3" suffix in its part number - denoting halogen-free, RoHS-compliant, and automotive-grade reliability testing. It meets stress test requirements for temperature cycling, humidity, and surge endurance, making it suitable for engine control, body electronics, and ADAS power domains.
What does the "HM3" suffix mean in SMAJ78AHM3/H?
The "HM3" suffix in SMAJ78AHM3/H specifies halogen-free, RoHS-compliant construction with AEC-Q101 qualification. Per Vishay's ordering information (Document 88390, page 3), HM3 denotes both environmental compliance and automotive-grade reliability validation - distinct from E3 (RoHS only) and HE3 (AEC-Q101 + RoHS, but not halogen-free).
Can SMAJ78AHM3/H be used in bidirectional configurations?
No, SMAJ78AHM3/H is a unidirectional TVS diode, as confirmed by its "A" suffix and cathode band marking. Bidirectional variants carry the "CA" suffix (e.g., SMAJ78CA). Using SMAJ78AHM3/H in reverse-biased AC applications would result in forward conduction and failure; always verify polarity during placement.
What is the maximum operating temperature for SMAJ78AHM3/H?
The SMAJ78AHM3/H has a maximum junction temperature (TJ max.) of +150 °C and an operating junction/storage temperature range of -55 °C to +150 °C. This rating supports deployment in under-hood automotive environments and thermally demanding industrial enclosures, provided PCB thermal design maintains RθJA ≤ 120 °C/W.
SMAJ78AHM3/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:
- Discontinued at Digi-Key
- 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/H FAQ
1.How can I place an order for SMAJ78AHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78AHM3/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/H reliable?
The price and inventory of SMAJ78AHM3/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/H is usually 5 days.
3.What payment methods are accepted for SMAJ78AHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78AHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78AHM3/H?
SMAJ78AHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78AHM3/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/H?
For technical support, including SMAJ78AHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78AHM3/H requirements.
6.How does Aetrix verify that SMAJ78AHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ78AHM3/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/H meets industry standards.
7.What is the process for return or replacement of SMAJ78AHM3/H?
All SMAJ78AHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78AHM3/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/H part is unused and in its original packaging.
Return procedure for SMAJ78AHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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