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Vishay General Semiconductor - Diodes Division SMAJ78AHM3/I
- Part No.:
- SMAJ78AHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78AHM3/I.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,384
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Product details
Overview
SMAJ78AHM3/I 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 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 (IPPM), and 400 W peak pulse power (10/1000 μs waveform) - suitable for protecting MOSFETs, ICs, and sensor interfaces in automotive and industrial power supplies.
For engineers reviewing the SMAJ78AHM3/I datasheet, SMAJ78AHM3/I pinout, SMAJ78AHM3/I application, or SMAJ78AHM3/I equivalent, this page delivers verified electrical specs, thermal derating behavior, AEC-Q101 qualification status, and precise clamping performance under standardized surge conditions - critical for ESD and load-dump protection design validation.
Technical Context
The SMAJ78AHM3/I operates as a unidirectional avalanche diode with cathode-band polarity marking, optimized for fast transient response (<1 ns) and low incremental surge resistance. Its junction temperature range spans –55 °C to +150 °C, and it delivers 3.2 A peak pulse current (IPPM) at 126 V clamping voltage under 10/1000 μs waveform, with thermal resistance RθJA = 120 °C/W on standard 0.2" × 0.2" copper pads.
Rated for 3.3 W steady-state power dissipation at 50 °C ambient, it supports repetitive surge duty cycles up to 0.01 % and meets J-STD-020 MSL Level 1 (260 °C reflow peak). 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 | 78 V - maximum continuous reverse operating voltage before significant leakage; defines safe DC/AC bias margin for protected line |
| VBR (min/max) | 86.7 V / 95.8 V at IT = 1 mA - guaranteed avalanche onset range; ensures predictable turn-on during overvoltage events |
| VC @ IPPM | 126 V at 3.2 A - clamped voltage seen by downstream circuitry during 10/1000 μs surge; limits stress on 100 V-rated components |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - peak transient energy absorption capability; enables robust protection against ISO 7637-2 Pulse 1/2a/5a |
| ID @ VWM | 1.0 μA - ultra-low reverse leakage at rated stand-off; minimizes standby power loss in battery-critical systems |
| TJ max. | +150 °C - maximum junction temperature; supports operation in under-hood automotive environments and sealed industrial enclosures |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline with 5.28 mm × 4.50 mm footprint and 2.29 mm height; compatible with automated pick-and-place |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated compound, cathode indicated by band on one end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side of protected line (e.g., ground or return path); conducts during forward surge or bias |
| Cathode | Avalanche clamping terminal | Connected to higher-potential side (e.g., supply rail or signal line); initiates clamping when reverse voltage exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Enables single-event suppression of 3.2 A surges without degradation - sufficient for ISO 16750-2 load dump simulation in 12 V systems |
| AEC-Q101 qualified (HM3 suffix) | Validated for automotive electronics per stress test requirements including HTOL, TCT, and ESD - supports ASIL-B system integration |
| MSL Level 1 moisture sensitivity | Allows unlimited floor life and standard 260 °C reflow without popcorn failure - eliminates baking requirement in SMT production |
| Glass passivated junction | Ensures stable VBR and low leakage over temperature and lifetime - critical for long-term reliability in industrial control modules |
| Halogen-free & RoHS-compliant (HM3) | Fulfills EU ELV and China RoHS environmental mandates while maintaining thermal and electrical performance parity with legacy variants |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Clamping |
|---|---|
|
Use Scenario: Suppressing load-dump transients (up to 35 V × 100 ms) on 12 V battery-fed ECUs and body control modules. IC Role / Device Role / Timing Role: Unidirectional TVS placed between VBAT and ground, clamping surges within 1 ns to protect LDOs and microcontrollers. Use Value: Limits peak rail voltage to ≤126 V during ISO 7637-2 Pulse 5a, preventing latch-up or gate oxide damage in 100 V-rated power FETs. |
Use Scenario: Guarding analog input pins of 24 V industrial PLC I/O modules against inductive switching noise from solenoid drivers. IC Role / Device Role / Timing Role: TVS connected anode-to-ground, cathode-to-signal line, shunting fast spikes before they reach ADC front-end op-amps. Use Value: Maintains signal integrity below 126 V clamping threshold while adding <1 pF capacitance - no bandwidth degradation in 10 kHz sensor signals. |
| DC-DC Converter Input Stage | Telecom Line Card Surge Defense |
|
Use Scenario: Protecting buck converter inputs in telecom power supplies subjected to lightning-induced surges on 48 V backplane rails. IC Role / Device Role / Timing Role: Primary clamping device upstream of input filter capacitor; absorbs energy before it reaches MOSFET gate drivers. Use Value: Withstands 300 W peak pulse above 78 V (per spec note), enabling compliance with IEC 61000-4-5 Level 3 (2 kV line-earth) when used with series impedance. |
Use Scenario: Safeguarding Ethernet PHY interface power pins in outdoor base station line cards exposed to induced surges via long cable runs. IC Role / Device Role / Timing Role: Standoff-rated TVS on 3.3 V/5 V auxiliary rails, coordinated with GDT or polymer PTC for multi-stage protection. Use Value: 1.0 μA leakage at 78 V ensures minimal impact on always-on management circuits; AEC-Q101 qualification adds confidence in field longevity. |
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/I | Same electrical specs and package; RoHS-compliant but not halogen-free; lacks AEC-Q101 qualification | Acceptable for commercial/industrial use where automotive reliability certification is not required | Select when cost sensitivity outweighs halogen-free or automotive qualification needs |
| SMAJ78A-M3/5A | Identical VWM/VBR/VC/PPPM; HM3 and M3 share halogen-free and RoHS compliance, but M3 is not AEC-Q101 qualified | Suitable for high-reliability industrial designs needing halogen-free materials but no automotive stress testing | Choose for halogen-free compliance without AEC-Q101 overhead; verify board-level qualification if deployed in automotive contexts |
Compared with SMAJ78AHM3/I, SMAJ78AHE3/I omits halogen-free construction and automotive qualification - reducing cost but limiting deployment to non-automotive applications; SMAJ78A-M3/5A provides halogen-free compliance without AEC-Q101 validation, making it appropriate for industrial environments requiring green materials but not automotive stress screening.
Availability
SMAJ78AHM3/I is available at Aetrix Electronics and suitable for automotive ECU protection, industrial PLC I/O hardening, and telecom power rail surge suppression requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SMAJ78AHM3/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 optimization.
The SMAJ series is engineered for high-energy transient suppression in harsh environments - targeting automotive, industrial, and telecom systems where consistent clamping performance and AEC-Q101 validation are mandatory.
FAQ
What is the clamping voltage of the SMAJ78AHM3/I under a 10/1000 μs surge?
The SMAJ78AHM3/I exhibits a maximum clamping voltage (VC) of 126 V at 3.2 A peak pulse current (IPPM) under the standardized 10/1000 μs waveform. This value is measured per Figure 1 and Table 1 in Vishay Document 88390, and defines the upper voltage limit imposed on protected circuitry during transient events - critical for ensuring downstream components remain within their absolute maximum ratings.
Is SMAJ78AHM3/I qualified for automotive applications?
Yes, SMAJ78AHM3/I is AEC-Q101 qualified, as confirmed by the "HM3" suffix in its ordering code and explicit notation in the Vishay datasheet revision 09-Jan-2024. This qualification covers stress tests including high-temperature operating life, temperature cycling, and ESD, making SMAJ78AHM3/I suitable for under-hood and chassis-mounted automotive electronics where reliability under thermal and mechanical stress is essential.
What does the "HM3" suffix mean in SMAJ78AHM3/I?
The "HM3" suffix in SMAJ78AHM3/I denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. Per Vishay's ordering information table, HM3 indicates compliance with JEDEC J-STD-020 MSL Level 1, whisker resistance per JESD 201 Class 2, and automotive-grade reliability testing - distinguishing it from E3 (RoHS only) and M3 (halogen-free/RoHS, non-automotive) variants.
Can SMAJ78AHM3/I be used in bidirectional configurations?
No, SMAJ78AHM3/I is a unidirectional TVS diode, as indicated by the "A" (not "CA") suffix and cathode-band marking. Bidirectional operation requires the "CA" variant (e.g., SMAJ78CA); using SMAJ78AHM3/I in reverse-biased AC applications would result in forward conduction and potential failure. Always match device polarity to circuit topology - SMAJ78AHM3/I protects against positive transients on the cathode side relative to anode.
What is the thermal resistance of SMAJ78AHM3/I, and how does it affect layout?
SMAJ78AHM3/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 Thermal Characteristics table. To maintain safe junction temperatures under sustained power dissipation, PCB layout must replicate this pad area - undersized traces or insufficient copper will elevate TJ beyond the +150 °C maximum and accelerate parametric drift or failure.
SMAJ78AHM3/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:
- 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/I FAQ
1.How can I place an order for SMAJ78AHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78AHM3/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 SMAJ78AHM3/I reliable?
The price and inventory of SMAJ78AHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78AHM3/I is usually 5 days.
3.What payment methods are accepted for SMAJ78AHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78AHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78AHM3/I?
SMAJ78AHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78AHM3/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 SMAJ78AHM3/I?
For technical support, including SMAJ78AHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78AHM3/I requirements.
6.How does Aetrix verify that SMAJ78AHM3/I is sourced from the original manufacturer or authorized distributors?
All SMAJ78AHM3/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 SMAJ78AHM3/I meets industry standards.
7.What is the process for return or replacement of SMAJ78AHM3/I?
All SMAJ78AHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78AHM3/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 SMAJ78AHM3/I part is unused and in its original packaging.
Return procedure for SMAJ78AHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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