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Vishay General Semiconductor - Diodes Division SMCJ78A-M3/57T
- Part No.:
- SMCJ78A-M3/57T
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78A-M3/57T.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:5,051
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Product details
Overview
SMCJ78A-M3/57T 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 standoff voltage (VWM), 86.7–95.8 V breakdown voltage (VBR), and 1500 W peak pulse power (PPPM) capability. It clamps transients to ≤126 V at 11.9 A peak pulse current (IPPM), and operates across -55 °C to +150 °C junction temperature range - used in automotive power rail and industrial sensor interface protection.
For engineers reviewing the SMCJ78A-M3/57T datasheet, SMCJ78A-M3/57T pinout, SMCJ78A-M3/57T application, or SMCJ78A-M3/57T equivalent, key selection considerations include its halogen-free RoHS-compliant M3 termination, 1.0 μA max reverse leakage at VWM, 0.106 %/°C VBR temperature coefficient, and AEC-Q101 qualification eligibility via HM3 suffix variants.
Technical Context
This TVS diode employs a glass-passivated silicon junction optimized for fast response (<1 ns) to transient overvoltages, with low incremental surge resistance enabling precise clamping under 10/1000 μs waveform stress. Its unidirectional polarity features a cathode band marking and supports surge currents up to 200 A (IFSM, 8.3 ms half-sine).
Thermally, it exhibits RθJA = 75 °C/W (junction-to-ambient, on recommended 8.0 mm × 8.0 mm copper pads) and RθJL = 15 °C/W (junction-to-lead), supporting reliable operation in compact PCB layouts without forced cooling. The device meets J-STD-020 MSL Level 1 and JESD201 Class 2 whisker resistance requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM (Stand-off Voltage) | 78 V - maximum continuous reverse operating voltage before significant conduction begins; defines safe operating margin below clamping threshold. |
| VBR (Breakdown Voltage) | 86.7–95.8 V at 1.0 mA test current - voltage at which device enters avalanche conduction; ensures predictable turn-on during transients. |
| VC (Clamping Voltage) | ≤126 V at IPPM = 11.9 A (10/1000 μs) - peak voltage seen by protected circuit during worst-case surge; critical for IC-level voltage tolerance compliance. |
| PPPM (Peak Pulse Power) | 1500 W - maximum non-repetitive surge energy absorption capacity; enables robust protection against lightning-induced or inductive-switching spikes. |
| ID (Reverse Leakage) | ≤1.0 μA at VWM = 78 V - minimal standby power loss and signal integrity impact in high-impedance circuits like sensor bias networks. |
| TJ max. | +150 °C - extended thermal operating range supports under-hood automotive and industrial environments without derating penalties. |
| Package | SMC (DO-214AB) - standardized surface-mount outline with 7.75 mm × 6.22 mm footprint and 2.62 mm height; compatible with automated pick-and-place and reflow. |
Pinout & Package
SMCJ78A-M3/57T uses the SMC (DO-214AB) package: a two-terminal surface-mount case with cathode band marking on the unidirectional variant. Terminals are matte tin-plated leads, solderable per J-STD-002 and JESD22-B102.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Anode of internal PN junction | Connected to protected circuit's positive rail or signal line; reverse-biased during normal operation; conducts during overvoltage events. |
| Anode (non-banded end) | Cathode of internal PN junction | Typically tied to ground or lower-potential reference; completes current path during clamping to shunt surge energy safely. |
Key Features
| Feature | Design Value |
|---|---|
| Halogen-free, RoHS-compliant construction | M3 suffix confirms full halogen-free material set and RoHS compliance - required for automotive and green electronics programs. |
| Low incremental surge resistance | Enables tight VC/VBR ratio (126 V / ~91 V ≈ 1.38), minimizing overshoot and ensuring downstream ICs remain within absolute maximum ratings. |
| Very fast response time | <1 ns turn-on - suppresses ESD and fast-rising transients before sensitive logic or analog front-ends are damaged. |
| MSL Level 1 moisture sensitivity | No dry-pack or baking required prior to reflow; simplifies manufacturing flow and reduces handling risk for high-volume SMT lines. |
| AEC-Q101 qualification pathway | HM3 suffix variants (e.g., SMCJ78AHM3_X) are AEC-Q101 qualified - enables drop-in use in automotive powertrain and body control modules. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface |
|---|---|
|
Use Scenario: Protecting 12 V/24 V battery-fed ECUs from load dump and alternator ripple transients per ISO 7637-2. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power input and ground to clamp surges above 78 V while remaining inert during nominal operation. Use Value: Withstands 1500 W pulses and clamps to ≤126 V, ensuring microcontrollers and CAN transceivers survive 12 V system transients up to ±100 V. |
Use Scenario: Shielding analog output lines (e.g., 4–20 mA current loops or 0–10 V signals) from ESD and field wiring faults in factory automation. IC Role / Device Role / Timing Role: TVS connected across signal and return paths to divert fast transients before they reach precision ADC inputs or op-amp buffers. Use Value: 1.0 μA leakage at 78 V prevents loading of high-impedance sensor outputs; 126 V clamping protects 16-bit DACs and instrumentation amplifiers. |
| Telecom Line Card Surge Protection | Consumer Power Adapter Input Stage |
|
Use Scenario: Safeguarding Ethernet PHY power supplies and PoE injectors against lightning-induced surges on DC input rails. IC Role / Device Role / Timing Role: Primary-stage TVS on 48 V input bus, upstream of DC/DC converters, to absorb bulk surge energy before regulation. Use Value: 1500 W PPPM rating handles IEC 61000-4-5 Level 4 (4 kV) surges; DO-214AB package allows dense layout near connector entry points. |
Use Scenario: Secondary-side overvoltage suppression on 5–24 V DC outputs of wall adapters and USB PD chargers. IC Role / Device Role / Timing Role: Unidirectional TVS placed across output terminals to prevent damage from reverse polarity connection or regulator failure. Use Value: 78 V VWM provides ample margin above 24 V nominal outputs; 126 V VC ensures connected devices (e.g., USB-C peripherals) avoid latch-up. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A-M3/57T | Lower PPPM (400 W), smaller SMA (DO-214AC) package, same VWM/VBR range. | Suitable only for lower-energy transients (e.g., ESD-only); not rated for ISO 7637-2 load dump. | Select when board space is constrained and surge threat level is limited to IEC 61000-4-2 ESD (±8 kV contact). |
| SMCJ78CA-M3/57T | Bidirectional variant; identical VWM/VBR specs but symmetric clamping in both polarities. | Required for AC-coupled or floating signal lines where polarity reversal is possible (e.g., RS-485, audio lines). | Choose for bidirectional protection needs; note that SMCJ78A-M3/57T cannot replace it in AC applications due to polarity limitation. |
Compared with SMAJ78A-M3/57T, SMCJ78A-M3/57T delivers 3.75× higher surge energy handling in the same mounting footprint family; versus SMCJ78CA-M3/57T, it offers lower capacitance and tighter leakage for DC-biased rails but lacks reverse-polarity protection.
Availability
SMCJ78A-M3/57T is available at Aetrix Electronics and suitable for automotive power distribution, industrial sensor interfaces, telecom line cards, and consumer power adapter designs requiring stable component supply and halogen-free compliance.
Supply support for SMCJ78A-M3/57T 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 SMCJ series is engineered for high-power transient suppression in harsh environments - targeting automotive, industrial, and telecom systems where robustness against repetitive surges and long-term stability are mandatory.
FAQ
What is the clamping voltage of SMCJ78A-M3/57T at its rated peak pulse current?
The SMCJ78A-M3/57T has a maximum clamping voltage (VC) of 126 V when subjected to its specified peak pulse current (IPPM) of 11.9 A under the standard 10/1000 μs waveform. This value is measured at TA = 25 °C on recommended 8.0 mm × 8.0 mm copper pads and defines the upper voltage limit imposed on protected circuitry during surge events. The SMCJ78A-M3/57T maintains this clamping performance across its full operating temperature range.
Is SMCJ78A-M3/57T suitable for automotive applications?
Yes - the SMCJ78A-M3/57T is halogen-free and RoHS-compliant (M3 suffix), and belongs to the AEC-Q101-qualified SMCJ family; while the base SMCJ78A-M3/57T itself is commercial-grade, its HM3-suffixed variants (e.g., SMCJ78AHM3_A) are fully AEC-Q101 qualified. Engineers deploying the SMCJ78A-M3/57T in automotive contexts must verify qualification status per ordering code and consult Vishay's automotive datasheet supplements. The SMCJ78A-M3/57T shares identical electrical specs with qualified versions.
How does the SMCJ78A-M3/57T differ from bidirectional SMCJ78CA-M3/57T?
The SMCJ78A-M3/57T is unidirectional with cathode band marking and blocks current in reverse bias until VBR is exceeded, whereas the SMCJ78CA-M3/57T is bidirectional with no polarity marking and clamps symmetrically in both directions. Their VWM (78 V), VBR (86.7–95.8 V), and VC (126 V) are identical, but the SMCJ78A-M3/57T exhibits lower junction capacitance and 1.0 μA leakage vs. 2.0 μA for the CA version. The SMCJ78A-M3/57T is intended for DC-biased rails; SMCJ78CA-M3/57T suits AC or floating lines.
What is the thermal resistance of SMCJ78A-M3/57T, and how does it affect PCB layout?
The SMCJ78A-M3/57T has a typical junction-to-ambient thermal resistance (RθJA) of 75 °C/W when mounted on minimum recommended 8.0 mm × 8.0 mm copper pads per terminal, and junction-to-lead resistance (RθJL) of 15 °C/W. This means effective heat dissipation requires adherence to Vishay's pad layout guidelines - undersized pads increase thermal impedance, risking junction overheating during repetitive surges. The SMCJ78A-M3/57T's thermal design directly impacts sustained surge duty cycle capability in real-world applications.
Does SMCJ78A-M3/57T require special handling or baking before reflow soldering?
No - the SMCJ78A-M3/57T is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life and may be placed directly into reflow without dry-packaging or baking. Its maximum peak reflow temperature is 260 °C, compatible with standard lead-free profiles. This eliminates moisture sensitivity concerns and streamlines SMT assembly for the SMCJ78A-M3/57T in high-volume manufacturing environments.
SMCJ78A-M3/57T 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-M3/57T FAQ
1.How can I place an order for SMCJ78A-M3/57T through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78A-M3/57T 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-M3/57T reliable?
The price and inventory of SMCJ78A-M3/57T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ78A-M3/57T is usually 5 days.
3.What payment methods are accepted for SMCJ78A-M3/57T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78A-M3/57T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78A-M3/57T?
SMCJ78A-M3/57T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78A-M3/57T 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-M3/57T?
For technical support, including SMCJ78A-M3/57T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78A-M3/57T requirements.
6.How does Aetrix verify that SMCJ78A-M3/57T is sourced from the original manufacturer or authorized distributors?
All SMCJ78A-M3/57T 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-M3/57T meets industry standards.
7.What is the process for return or replacement of SMCJ78A-M3/57T?
All SMCJ78A-M3/57T units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78A-M3/57T, 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-M3/57T part is unused and in its original packaging.
Return procedure for SMCJ78A-M3/57T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMCJ78A-M3/57T Tags
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