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Vishay General Semiconductor - Diodes Division SMCJ78A-M3/9AT
- Part No.:
- SMCJ78A-M3/9AT
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78A-M3/9AT.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:8,231
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Product details
Overview
SMCJ78A-M3/9AT from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in SMC (DO-214AB) package, designed for high-energy surge protection with 78 V stand-off voltage (VWM), 86.7–95.8 V breakdown voltage (VBR), and 1500 W peak pulse power (PPPM) at 10/1000 µs. It clamps transients to ≤126 V at 11.9 A IPPM and operates from –55 °C to +150 °C, commonly used to protect MOSFETs and signal lines in industrial power supplies.
For engineers reviewing the SMCJ78A-M3/9AT datasheet, SMCJ78A-M3/9AT pinout, SMCJ78A-M3/9AT application, or SMCJ78A-M3/9AT equivalent, key selection criteria include clamping voltage (VC = 126 V), unidirectional polarity, halogen-free RoHS-compliant M3 suffix, and compatibility with automated SMT assembly on 8.0 mm × 8.0 mm copper pads.
Technical Context
The SMCJ78A-M3/9AT employs a glass-passivated silicon junction optimized for fast response (<1 ns) to ESD and lightning-induced surges. Its low incremental surge resistance ensures stable clamping under repetitive 10/1000 µs transients, while thermal resistance (RθJA = 75 °C/W) supports operation up to 150 °C junction temperature without derating on standard PCB layouts.
Designed per ANSI/IEEE C62.35, it delivers precise bidirectional-capable electrical behavior only in CA variants; this unidirectional variant uses cathode-band marking and exhibits forward voltage VF = 3.5 V at 100 A, enabling use in DC-biased protection paths where reverse leakage (ID ≤ 1.0 µA at 78 V) must remain minimal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins; sets upper limit for protected circuit DC bias. |
| VBR min/max | 86.7 V / 95.8 V - Breakdown occurs within this range at 1 mA test current; defines onset of avalanche conduction. |
| VC @ IPPM | 126 V - Clamped voltage at 11.9 A peak pulse current; determines maximum stress imposed on downstream ICs. |
| PPPM | 1500 W - Peak pulse power handling with 10/1000 µs waveform; validates robustness against IEC 61000-4-5 Level 4 surges. |
| Package | SMC (DO-214AB) - Standardized 2-pin surface-mount outline with 7.75 mm × 6.22 mm footprint and 2.62 mm height; compatible with J-STD-020 MSL level 1 reflow. |
| Polarity | Unidirectional - Cathode marked by band; blocks reverse current until VBR exceeded, then clamps positive transients to ground. |
| TJ max | +150 °C - Maximum junction temperature; enables deployment in under-hood automotive or high-ambient industrial environments. |
Pinout & Package
SMCJ78A-M3/9AT uses the SMC (DO-214AB) package: a rectangular surface-mount case with two coplanar matte tin-plated leads, 0.220–0.246 inch wide, 0.305–0.320 inch long, and 0.079–0.103 inch high. Polarity is indicated by a cathode band on the body end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input/Line side terminal | Connected to protected line (e.g., DC bus or signal trace); carries surge current into device during overvoltage events. |
| Cathode | Ground-reference terminal | Connected to system ground or low-impedance return path; provides reference for clamping action and defines unidirectional conduction direction. |
Key Features
| Feature | Design Value |
|---|---|
| Halogen-free & RoHS-compliant | M3 suffix confirms compliance with JEDEC J-STD-201 Class 2 whisker resistance and EU RoHS Directive 2011/65/EU, supporting green manufacturing. |
| Low incremental surge resistance | Enables tight VC tolerance (126 V at 11.9 A), minimizing voltage overshoot during fast-rising transients like EFT or ISO 7637-2 pulses. |
| MSL Level 1 rating | Allows unlimited floor life and standard reflow profiles up to 260 °C peak, eliminating bake requirements prior to SMT assembly. |
| 1500 W peak pulse power | Supports protection of 24 V/48 V industrial control inputs against 4 kV/2 kA IEC 61000-4-5 combination wave surges without external series impedance. |
Applications
| Industrial Motor Drives | Automotive Body Control Modules |
|---|---|
Use Scenario: Protection of gate drivers and IGBTs against inductive kickback from relay coils and solenoid loads in PLC output stages. IC Role / Device Role / Timing Role: Unidirectional TVS placed across DC bus rails to clamp switching spikes before they reach power semiconductors. Use Value: Limits transient voltage to ≤126 V, preventing gate oxide rupture in 100 V-rated MOSFETs and ensuring >100,000-cycle reliability under 100 A surge conditions. | Use Scenario: Safeguarding LIN bus transceivers and microcontroller I/O pins from load dump and jump-start surges in door module ECUs. IC Role / Device Role / Timing Role: Standoff-clamp TVS connected between LIN line and chassis ground, activated only during >78 V overvoltage events. Use Value: Maintains <1.0 µA leakage at 13.5 V nominal supply, preserving bus quiescent current budget while surviving 35 V/100 ms load dump per ISO 16750-2. |
| Telecom Power Rectifiers | Medical Imaging Power Supplies |
Use Scenario: Secondary-side surge suppression on +48 V telecom rectifier outputs feeding PoE injectors and baseband processors. IC Role / Device Role / Timing Role: Primary overvoltage clamp on DC distribution rail upstream of DC-DC converters and hot-swap controllers. Use Value: Withstands repeated 1500 W surges without parameter shift, meeting GR-1089-CORE immunity requirements for central office equipment. | Use Scenario: Input-stage protection for isolated 200–300 V DC-DC converters powering X-ray detector ASICs and analog front-ends. IC Role / Device Role / Timing Role: High-voltage standoff TVS bridging primary-to-secondary isolation barrier to shunt common-mode transients. Use Value: 126 V clamping ensures secondary-side components see no more than rated stress, supporting IEC 60601-1 4th edition creepage/clearance compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78A-M3/57T | Same VWM/VBR/VC specs but SMB (DO-214AA) package; 600 W PPPM rating vs. 1500 W. | Limited to lower-energy surges (IEC 61000-4-5 Level 2); unsuitable for 48 V industrial bus protection requiring full 1500 W margin. | Select only when board space constraints prohibit SMC footprint and surge threat level is ≤600 W. |
| SMCJ78CA-M3/9AT | Bidirectional variant with identical VWM/VBR/VC but symmetrical clamping in both polarities; same 1500 W rating. | Required for AC-coupled or floating signal lines (e.g., RS-485, CAN FD) where negative transients occur. | Choose when protecting differential buses or circuits lacking defined ground reference; not drop-in for unidirectional DC paths. |
Compared with SMBJ78A-M3/57T and SMCJ78CA-M3/9AT, the SMCJ78A-M3/9AT uniquely balances high 1500 W surge capacity with unidirectional DC rail protection in the industry-standard SMC package-making it optimal for cost-sensitive, high-reliability 78 V DC systems where polarity is fixed and energy threats exceed 1 kW.
Availability
SMCJ78A-M3/9AT is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, and telecom power rectifiers requiring stable component supply, halogen-free compliance, and MSL Level 1 reflow capability.
Supply support for SMCJ78A-M3/9AT 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 AEC-Q101 qualification.
The SMCJ series targets high-energy transient suppression in harsh environments, engineered specifically for industrial automation, automotive subsystems, and telecom infrastructure where sustained surge immunity and thermal stability are critical.
FAQ
What is the clamping voltage of the SMCJ78A-M3/9AT at its rated peak pulse current?
The SMCJ78A-M3/9AT clamps to a maximum of 126 V at its specified peak pulse current (IPPM) of 11.9 A under a 10/1000 µs waveform. This value is measured per ANSI/IEEE C62.35 and reflects worst-case voltage seen by protected circuitry during surge events. The SMCJ78A-M3/9AT maintains this clamping performance across its full operating temperature range (–55 °C to +150 °C) when mounted on recommended 8.0 mm × 8.0 mm copper pads.
Does the SMCJ78A-M3/9AT meet automotive qualification standards?
The SMCJ78A-M3/9AT itself is not AEC-Q101 qualified; that status applies only to variants with HE3 or HM3 suffixes (e.g., SMCJ78A-HE3). However, the SMCJ78A-M3/9AT shares identical die, packaging, and electrical characteristics with its AEC-Q101 counterparts-differing only in traceability documentation and lot-level testing. For non-safety-critical automotive applications such as body electronics, the SMCJ78A-M3/9AT is widely deployed with internal qualification.
How does the M3 suffix affect the SMCJ78A-M3/9AT's environmental compliance?
The M3 suffix on SMCJ78A-M3/9AT indicates halogen-free, RoHS-compliant construction per JEDEC J-STD-201 Class 2 whisker resistance and EU Directive 2011/65/EU Annex II. Unlike E3-suffix parts, M3 devices eliminate brominated flame retardants and chlorine-based compounds from molding compounds and plating, reducing toxic gas emission during PCB rework or end-of-life incineration-critical for medical and consumer electronics.
Can the SMCJ78A-M3/9AT be used in bidirectional signal protection?
No-the SMCJ78A-M3/9AT is strictly unidirectional and features a cathode band marking; applying reverse voltage beyond its 78 V stand-off rating will cause breakdown and potential failure. For bidirectional protection (e.g., RS-485, USB, or AC lines), the SMCJ78CA-M3/9AT variant must be selected. Using the SMCJ78A-M3/9AT in bidirectional configurations risks asymmetric clamping and irreversible degradation.
What is the thermal resistance from junction to ambient for the SMCJ78A-M3/9AT?
The SMCJ78A-M3/9AT has a typical junction-to-ambient thermal resistance (RθJA) of 75 °C/W when mounted on the minimum recommended pad layout (0.31" × 0.31" copper pads per terminal). This value assumes still air convection and no heatsink; actual RθJA improves with larger copper areas or forced airflow. The SMCJ78A-M3/9AT's 150 °C maximum junction temperature allows operation at full 1500 W surge rating up to +85 °C ambient with proper PCB layout.
SMCJ78A-M3/9AT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-214AB, SMC
- 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):
- 11.9A
- Power - Peak Pulse:
- 1500W (1.5kW)
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMC)
SMCJ78A-M3/9AT FAQ
1.How can I place an order for SMCJ78A-M3/9AT through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78A-M3/9AT 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 SMCJ78A-M3/9AT reliable?
The price and inventory of SMCJ78A-M3/9AT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ78A-M3/9AT is usually 5 days.
3.What payment methods are accepted for SMCJ78A-M3/9AT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78A-M3/9AT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78A-M3/9AT?
SMCJ78A-M3/9AT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78A-M3/9AT 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 SMCJ78A-M3/9AT?
For technical support, including SMCJ78A-M3/9AT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78A-M3/9AT requirements.
6.How does Aetrix verify that SMCJ78A-M3/9AT is sourced from the original manufacturer or authorized distributors?
All SMCJ78A-M3/9AT 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 SMCJ78A-M3/9AT meets industry standards.
7.What is the process for return or replacement of SMCJ78A-M3/9AT?
All SMCJ78A-M3/9AT units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78A-M3/9AT, 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 SMCJ78A-M3/9AT part is unused and in its original packaging.
Return procedure for SMCJ78A-M3/9AT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMCJ78A-M3/9AT Tags
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