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Vishay General Semiconductor - Diodes Division SMCJ78CA-M3/9AT
- Part No.:
- SMCJ78CA-M3/9AT
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78CA-M3/9AT.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:5,393
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Product details
Overview
SMCJ78CA-M3/9AT from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMC (DO-214AB) package, designed for high-energy surge protection with 78 V standoff voltage (VWM), 1500 W peak pulse power (PPPM), and 126 V clamping voltage (VC) at 11.9 A peak pulse current (IPPM). It protects sensitive signal lines and power rails in automotive sensor interfaces, industrial I/O modules, and telecom line cards against ESD and inductive switching transients.
For engineers reviewing the SMCJ78CA-M3/9AT datasheet, SMCJ78CA-M3/9AT pinout, SMCJ78CA-M3/9AT application, or SMCJ78CA-M3/9AT equivalent, this device delivers verified bidirectional clamping performance, halogen-free RoHS compliance (M3 suffix), and AEC-Q101 qualification readiness - critical for automotive-grade board-level surge resilience and long-term supply stability.
Technical Context
The SMCJ78CA-M3/9AT operates as a silicon avalanche diode with symmetrical breakdown behavior in both directions, enabling robust protection of AC-coupled or differential signal paths without polarity constraints. Its glass-passivated junction ensures stable VBR (86.7–95.8 V) and low incremental surge resistance, while MSL Level 1 rating supports lead-free reflow up to 260 °C.
Designed for unclamped transient suppression per IEC 61000-4-5 (10/1000 µs waveform), it maintains clamping voltage ≤126 V at 11.9 A IPPM and exhibits a temperature coefficient of VBR at +0.106 %/°C - enabling predictable performance across -55 °C to +150 °C operating junction range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous reverse working voltage before clamping begins; defines safe operating margin for 72–84 V nominal rail systems. |
| VBR min/max | 86.7 V / 95.8 V - breakdown voltage range at 1 mA test current; ensures reliable turn-on within defined tolerance band. |
| VC @ IPPM | 126 V - clamping voltage at 11.9 A peak pulse current (10/1000 µs); limits downstream voltage stress during surge events. |
| PPPM | 1500 W - peak pulse power handling capability; supports high-energy transients common in automotive load-dump and industrial motor switching. |
| TJ max | +150 °C - maximum junction temperature; enables operation in under-hood automotive environments and enclosed industrial enclosures. |
| Package | SMC (DO-214AB) - surface-mount package with 8.0 mm × 8.0 mm copper pad thermal footprint; optimized for automated placement and thermal dissipation. |
Pinout & Package
SMCJ78CA-M3/9AT uses the SMC (DO-214AB) package: a 2-terminal, non-polarized surface-mount case with matte tin-plated leads solderable per J-STD-002. Bidirectional construction means no cathode/anode marking; terminals are electrically symmetric.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Terminal 1 | Anode/Cathode (bidirectional) | Either terminal serves as input/output path for transient energy; no polarity dependency - connects directly across protected line pair (e.g., RS-485 A/B). |
| Terminal 2 | Anode/Cathode (bidirectional) | Electrically identical to Terminal 1; forms symmetrical clamping path - requires no orientation during PCB layout or assembly. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC signals, differential buses (CAN, RS-485), and floating power domains without external polarity management. |
| 1500 W peak pulse power | Withstands 10/1000 µs surges up to 11.9 A - exceeds IEC 61000-4-5 Level 4 requirements for industrial and automotive applications. |
| Halogen-free & RoHS-compliant (M3) | Meets global environmental regulations and JESD201 Class 2 whisker resistance - suitable for high-reliability consumer, medical, and automotive production. |
| MSL Level 1, 260 °C peak | Supports standard lead-free reflow profiles without moisture sensitivity concerns - eliminates bake requirements and reduces manufacturing risk. |
Applications
| Automotive Sensor Interface | Industrial RS-485 Communication |
|---|---|
Use Scenario: Protecting LIN/CAN transceiver inputs and analog sensor outputs (e.g., pressure, temperature) from battery dump and load-switching spikes in engine control units. IC Role / Device Role / Timing Role: Bidirectional TVS clamping element placed directly at connector entry point, shunting transients before they reach signal conditioning ICs. Use Value: Limits voltage excursion to ≤126 V during 10/1000 µs surges, preserving signal integrity and preventing latch-up in 5 V or 12 V sensor front-ends. | Use Scenario: Safeguarding RS-485 transceivers on factory-floor PLC I/O modules exposed to motor drive noise and ground bounce. IC Role / Device Role / Timing Role: Differential-line protector across A/B bus pairs, absorbing common-mode and differential-mode surges without distorting data timing. Use Value: Maintains <1 ns response time and ≤126 V clamping to prevent bit errors and transceiver damage during 4 kV contact ESD or 2 kV surge events. |
| Telecom Line Card Protection | Power Supply Input Stage |
Use Scenario: Shielding Ethernet PHYs and PoE injectors on telecom access equipment from lightning-induced surges on twisted-pair lines. IC Role / Device Role / Timing Role: Primary surge limiter at line-side interface, coordinated with GDT or MOV secondary stages for multi-level protection architecture. Use Value: Delivers 1500 W pulse handling and 78 V VWM - compatible with 48 V DC bias while clamping induced transients below IC absolute maximum ratings. | Use Scenario: Guarding 72–84 V intermediate bus inputs in industrial SMPS designs against inductive kickback from relay coils or solenoid drivers. IC Role / Device Role / Timing Role: Standoff-rated overvoltage clamp placed after bulk filter but before primary controller IC, absorbing stored inductive energy. Use Value: Withstands 200 A IFSM (unidirectional reference) and maintains stable VBR across temperature - ensuring consistent trip threshold in high-ambient environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78CA-M3/57T | Same VWM (78 V), lower PPPM (600 W), SMB package (smaller footprint, higher RθJA). | Limited to lower-energy transients; unsuitable for IEC 61000-4-5 Level 4 or automotive load-dump. | Select only when space-constrained and surge threat level is ≤600 W. |
| SMCJ78A-M3/9AT | Unidirectional version; same VWM, PPPM, and package; includes cathode band marking. | Requires polarity-aware layout; not usable on AC or differential lines without external diodes. | Choose only for DC-biased single-ended rails where polarity is fixed and known. |
Compared with SMBJ78CA-M3/57T and SMCJ78A-M3/9AT, the SMCJ78CA-M3/9AT uniquely combines bidirectional symmetry, 1500 W surge capacity, and halogen-free SMC packaging - making it the only option among the three qualified for high-energy, polarity-agnostic protection in automotive and industrial edge nodes.
Availability
SMCJ78CA-M3/9AT is available at Aetrix Electronics and suitable for automotive sensor interfaces, industrial RS-485 networks, and telecom line card protection requiring stable component supply, long-term lifecycle support, and halogen-free compliance.
Supply support for SMCJ78CA-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 application-specific optimization.
The SMCJ series is part of Vishay's TRANSZORB® TVS platform, engineered specifically for high-power transient suppression in harsh environments including automotive, industrial automation, and telecommunications infrastructure.
FAQ
What does the "CA" suffix indicate in SMCJ78CA-M3/9AT?
The "CA" suffix denotes a bidirectional configuration - meaning the SMCJ78CA-M3/9AT provides symmetrical clamping in both forward and reverse directions. This allows it to protect AC-coupled signals, differential buses like RS-485 or CAN, and floating power domains without polarity constraints. Unlike unidirectional variants (e.g., SMCJ78A), the SMCJ78CA-M3/9AT has no cathode marking and functions identically regardless of terminal orientation.
Is SMCJ78CA-M3/9AT qualified for automotive use?
The SMCJ78CA-M3/9AT is halogen-free and RoHS-compliant (M3 suffix), and belongs to the AEC-Q101-qualified SMCJ family. While the base P/N-M3 variant itself is commercial grade, Vishay offers AEC-Q101 versions under HM3 suffix (e.g., SMCJ78CAHM3_X). For full automotive qualification, specify the HM3 variant; the SMCJ78CA-M3/9AT remains suitable for non-safety-critical automotive subsystems where M3 compliance meets program requirements.
What is the clamping voltage of SMCJ78CA-M3/9AT and how is it measured?
The SMCJ78CA-M3/9AT has a maximum clamping voltage (VC) of 126 V, measured at 11.9 A peak pulse current (IPPM) using a standardized 10/1000 µs double-exponential surge waveform. This value represents the upper limit of voltage seen by downstream circuitry during worst-case transient events and is guaranteed across the full operating temperature range (-55 °C to +150 °C).
Can SMCJ78CA-M3/9AT be used in place of a unidirectional TVS like SMCJ78A-M3/9AT?
The SMCJ78CA-M3/9AT can replace SMCJ78A-M3/9AT only in circuits where polarity is undefined or bidirectional operation is required - such as differential data lines or AC-coupled rails. In DC-biased single-ended applications, the unidirectional SMCJ78A-M3/9AT offers tighter leakage control and avoids unnecessary conduction during normal forward bias. Substitution requires layout review to confirm absence of cathode-dependent routing.
What is the thermal resistance and how does it affect PCB layout for SMCJ78CA-M3/9AT?
The SMCJ78CA-M3/9AT 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. To maintain TJ ≤150 °C under 6.5 W steady-state dissipation, PCB layout must provide adequate copper area and avoid thermal bottlenecks. Reducing pad size or omitting thermal vias increases junction temperature and de-rates surge capability - especially critical in high-ambient industrial deployments.
SMCJ78CA-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:
- -
- Bidirectional Channels:
- 1
- 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)
SMCJ78CA-M3/9AT FAQ
1.How can I place an order for SMCJ78CA-M3/9AT through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78CA-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 SMCJ78CA-M3/9AT reliable?
The price and inventory of SMCJ78CA-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 SMCJ78CA-M3/9AT is usually 5 days.
3.What payment methods are accepted for SMCJ78CA-M3/9AT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78CA-M3/9AT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78CA-M3/9AT?
SMCJ78CA-M3/9AT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78CA-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 SMCJ78CA-M3/9AT?
For technical support, including SMCJ78CA-M3/9AT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78CA-M3/9AT requirements.
6.How does Aetrix verify that SMCJ78CA-M3/9AT is sourced from the original manufacturer or authorized distributors?
All SMCJ78CA-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 SMCJ78CA-M3/9AT meets industry standards.
7.What is the process for return or replacement of SMCJ78CA-M3/9AT?
All SMCJ78CA-M3/9AT units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78CA-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 SMCJ78CA-M3/9AT part is unused and in its original packaging.
Return procedure for SMCJ78CA-M3/9AT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMCJ78CA-M3/9AT Tags
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