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Vishay General Semiconductor - Diodes Division SMCJ78A-E3/57T
- Part No.:
- SMCJ78A-E3/57T
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78A-E3/57T.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:281
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Product details
Overview
SMCJ78A-E3/57T from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 78 V standoff voltage (VWM), 86.7–95.8 V breakdown range (VBR at 1 mA), 1500 W peak pulse power (10/1000 µs), 126 V clamping voltage at 11.9 A surge current, and operates from –55 °C to +150 °C. It is deployed in automotive power supply inputs and industrial sensor interfaces where ESD and load-dump transients must be suppressed without affecting normal operation.
For engineers reviewing the SMCJ78A-E3/57T datasheet, SMCJ78A-E3/57T pinout, SMCJ78A-E3/57T application, or SMCJ78A-E3/57T equivalent, key selection criteria include clamping voltage margin relative to protected IC's absolute maximum rating, thermal resistance (RθJA = 75 °C/W), unidirectional polarity marking, SMC (DO-214AB) package compatibility with automated placement, and AEC-Q101 qualification path via HE3 suffix variants.
Technical Context
The SMCJ78A-E3/57T employs a glass-passivated silicon junction optimized for fast response (<1 ps) to transient events such as ISO 7637-2 load dump (up to 120 V) and IEC 61000-4-2 ESD (±15 kV air). Its low incremental surge resistance ensures minimal voltage overshoot during high-current surges up to 11.9 A (10/1000 µs).
Designed for surface-mount use on 8.0 mm × 8.0 mm copper pads per terminal, it achieves 6.5 W steady-state power dissipation at TA = 50 °C and meets J-STD-020 MSL Level 1 (peak reflow ≤ 260 °C). Polarity is indicated by a cathode band; no marking is used for bidirectional variants.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before significant leakage; sets upper limit for protected circuit's nominal DC rail. |
| VBR (min/max) | 86.7 V / 95.8 V at 1 mA - Confirmed breakdown threshold range; ensures reliable turn-on above VWM with margin against tolerance drift. |
| VC @ IPPM | 126 V at 11.9 A - Clamped voltage during 1500 W transient; must remain below downstream IC's absolute max rating (e.g., <130 V for 12 V systems). |
| PPPM | 1500 W - Peak pulse power handling (10/1000 µs waveform); supports automotive load-dump immunity per ISO 7637-2 Pulse 5a. |
| RθJA | 75 °C/W - Junction-to-ambient thermal resistance on standard PCB pad layout; determines safe derating above 25 °C ambient. |
| TJ max | +150 °C - Maximum junction temperature; enables operation in under-hood automotive environments and industrial enclosures. |
| Package | SMC (DO-214AB) - Standardized 2-pin surface-mount outline with 7.75 mm × 6.22 mm footprint; compatible with JEDEC MS-013AC and automated pick-and-place. |
Pinout & Package
SMCJ78A-E3/57T uses the SMC (DO-214AB) package: a rectangular, molded plastic case with two coplanar matte tin-plated leads, cathode identified by a visible band. Leads meet J-STD-002 solderability and JESD 22-B102 whisker resistance Class 2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side connection point | Connected to ground or low-impedance return path; completes conduction path during reverse-biased transient clamp. |
| Cathode | High-side connection point | Marked with band; connected to protected line (e.g., 78 V rail input); blocks forward current but conducts reverse surge to ground. |
Key Features
| Feature | Design Value |
|---|---|
| 1500 W peak pulse power | Withstands automotive load-dump transients (ISO 7637-2 Pulse 5a) without degradation when mounted on recommended 8 mm × 8 mm copper pads. |
| 126 V clamping voltage at 11.9 A | Provides defined overvoltage ceiling during surge, enabling precise margining against 130 V-rated downstream components. |
| Glass-passivated junction | Ensures stable VBR and low leakage (<1 µA at 78 V) across temperature and lifetime, critical for long-term reliability in industrial control. |
| MSL Level 1 moisture sensitivity | Allows unlimited floor life and standard reflow profile (≤260 °C peak), eliminating bake requirements and simplifying SMT manufacturing. |
| RoHS-compliant, halogen-free option available | E3 suffix denotes commercial-grade RoHS compliance; M3 suffix adds halogen-free status-both meet environmental mandates without performance trade-offs. |
Applications
| Automotive Power Input Protection | Industrial Sensor Signal Line Clamp |
|---|---|
|
Use Scenario: Protecting 78 V battery-fed ECUs against ISO 7637-2 load-dump transients in commercial vehicle electronics. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between battery rail and DC-DC converter input, conducting only during overvoltage events. Use Value: Limits clamped voltage to 126 V, preserving converter IC integrity while surviving repeated 1500 W pulses without parameter shift. |
Use Scenario: Shielding analog output lines of pressure sensors in factory automation PLC modules from inductive switching noise. IC Role / Device Role / Timing Role: Low-capacitance (typ. <100 pF) unidirectional clamp referenced to system ground, shunting transients before reaching ADC front-end. Use Value: Maintains signal fidelity with <1 µA leakage at 78 V and sub-nanosecond response, preventing false readings during relay coil de-energization. |
| Telecom DC Power Feeds | Renewable Energy Charge Controller Inputs |
|
Use Scenario: Safeguarding 48–78 V telecom rectifier outputs from lightning-induced surges on outdoor cabinet power distribution. IC Role / Device Role / Timing Role: Primary overvoltage suppression device in series with bulk capacitance, absorbing energy before upstream fusing. Use Value: Delivers 1500 W pulse rating with 75 °C/W thermal resistance, enabling natural convection cooling in sealed enclosures. |
Use Scenario: Protecting MPPT controller inputs connected to photovoltaic arrays exposed to rapid irradiance changes and grid-switching transients. IC Role / Device Role / Timing Role: Standoff-rated TVS placed across PV+ and PV− terminals, blocking normal operation but clamping >78 V spikes. Use Value: Operates reliably from –55 °C to +150 °C, supporting desert and arctic deployments without derating or thermal runaway risk. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ78A | Same VWM (78 V), slightly higher VC (129 V @ 11.5 A), identical SMC package and 1500 W rating. | Marginally lower surge current handling (11.5 A vs. 11.9 A); requires verification of clamping margin in 130 V-tolerant designs. | Select when cross-sourcing Littelfuse-based BOMs or qualifying dual-source supply chains for telecom infrastructure. |
| ON Semiconductor 1.5SMC78A | Identical VWM, VBR, and PPPM; differs in thermal resistance (RθJA = 80 °C/W vs. 75 °C/W) and JEDEC registration code. | Slightly reduced thermal margin at elevated ambient; may require larger copper area or forced airflow in high-TA environments. | Prefer for legacy ON Semi design-in continuity or where existing 1.5SMC footprint validation exists. |
Compared with Littelfuse SMAJ78A and ON Semi 1.5SMC78A, the SMCJ78A-E3/57T offers the lowest clamping voltage (126 V) and best thermal resistance (75 °C/W), making it optimal for space-constrained, high-temperature applications where voltage margin and self-heating are critical.
Availability
SMCJ78A-E3/57T is available at Aetrix Electronics and suitable for automotive ECU power inputs, industrial sensor interface protection, and telecom DC feed applications requiring stable component supply, consistent parametric performance, and full traceability.
Supply support for SMCJ78A-E3/57T 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, MOSFETs, optoelectronics, and passive components with emphasis on reliability, precision, and ruggedized packaging.
The SMCJ series was engineered specifically for high-energy transient suppression in harsh environments-including automotive, industrial, and telecom-balancing clamping performance, thermal robustness, and automated manufacturability in the SMC package.
FAQ
What is the maximum clamping voltage of the SMCJ78A-E3/57T during a 1500 W transient event?
The SMCJ78A-E3/57T clamps to 126 V at its rated peak pulse current of 11.9 A (10/1000 µs waveform). This value is measured under standardized test conditions with the device mounted on 8.0 mm × 8.0 mm copper pads per terminal. The 126 V clamping voltage defines the upper voltage limit imposed on protected circuitry during surge events and must be validated against the absolute maximum ratings of downstream components in the SMCJ78A-E3/57T application.
Is the SMCJ78A-E3/57T suitable for automotive under-hood applications?
Yes, the SMCJ78A-E3/57T supports operation from –55 °C to +150 °C and is constructed with a glass-passivated junction and MSL Level 1 reflow compatibility-key requirements for under-hood deployment. While the base E3 suffix is commercial grade, Vishay offers AEC-Q101 qualified versions (e.g., SMCJ78AHE3) with the same electrical specs. For production automotive use, engineers should specify the HE3 variant and confirm qualification documentation, but the SMCJ78A-E3/57T itself provides the thermal and electrical foundation required.
How does the SMCJ78A-E3/57T differ from bidirectional variants like SMCJ78CA?
The SMCJ78A-E3/57T is unidirectional and features a cathode band for polarity identification; it blocks forward current and clamps only reverse transients. In contrast, SMCJ78CA is bidirectional, has no polarity marking, and clamps transients of either polarity-making it suitable for AC lines or differential signal pairs. Their VWM, VBR, and PPPM are identical, but the SMCJ78A-E3/57T delivers lower leakage (<1 µA at 78 V) in forward bias and is preferred for DC rail protection where polarity is fixed.
What is the thermal resistance of the SMCJ78A-E3/57T, and how does it affect PCB layout?
The SMCJ78A-E3/57T 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" (8.0 mm × 8.0 mm) copper areas per terminal. This value assumes no additional thermal vias or heatsinking. To maintain safe junction temperatures, designers must ensure adequate copper area and consider ambient temperature derating-especially above 50 °C, where its steady-state power dissipation drops from 6.5 W. Layout deviations directly impact thermal performance and long-term reliability of the SMCJ78A-E3/57T.
Can the SMCJ78A-E3/57T replace older 1N6277A or P6KE78A devices in existing designs?
The SMCJ78A-E3/57T is not a direct drop-in replacement for through-hole devices like 1N6277A or P6KE78A due to its SMC (DO-214AB) surface-mount package versus DO-204AC (Axial) or DO-15 packages. However, electrically it exceeds both: higher PPPM (1500 W vs. 600 W for P6KE78A), tighter VBR tolerance, and superior thermal performance. Migration requires PCB redesign for SMC footprint and reflow process validation-but delivers improved surge robustness and automated assembly compatibility in new SMCJ78A-E3/57T implementations.
SMCJ78A-E3/57T 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 (SMCJ)
SMCJ78A-E3/57T FAQ
1.How can I place an order for SMCJ78A-E3/57T through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78A-E3/57T 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-E3/57T reliable?
The price and inventory of SMCJ78A-E3/57T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ78A-E3/57T is usually 5 days.
3.What payment methods are accepted for SMCJ78A-E3/57T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78A-E3/57T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78A-E3/57T?
SMCJ78A-E3/57T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78A-E3/57T 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-E3/57T?
For technical support, including SMCJ78A-E3/57T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78A-E3/57T requirements.
6.How does Aetrix verify that SMCJ78A-E3/57T is sourced from the original manufacturer or authorized distributors?
All SMCJ78A-E3/57T 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-E3/57T meets industry standards.
7.What is the process for return or replacement of SMCJ78A-E3/57T?
All SMCJ78A-E3/57T units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78A-E3/57T, 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-E3/57T part is unused and in its original packaging.
Return procedure for SMCJ78A-E3/57T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMCJ78A-E3/57T Tags
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