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Taiwan Semiconductor Corporation SMCJ78CA
- Part No.:
- SMCJ78CA
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78CA.pdf
- Description:
- TVS DIODE 78VWM 126VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:3,087
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Product details
Overview
SMCJ78CA from Taiwan Semiconductor is a bidirectional 1500W transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with 78V working stand-off voltage (VWM), 86.7–106V breakdown voltage (VBR), and 139V maximum clamping voltage (VC) at 11.3A peak pulse current - designed for automotive load-dump and inductive switching protection in power supply rails and CAN/LIN interfaces.
For engineers reviewing the SMCJ78CA datasheet, SMCJ78CA pinout, SMCJ78CA application, or SMCJ78CA equivalent, key selection criteria include bidirectional clamping capability, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, sub-1ps response time, <1µA reverse leakage above 10V, and DO-214AB thermal performance (RθJA = 55°C/W).
Technical Context
The SMCJ78CA operates as a bipolar avalanche diode, symmetrically clamping transients in both forward and reverse directions without polarity dependence. Its glass-passivated junction enables stable VBR tolerance (±10% typical) and low leakage (<1µA @ VWM), while meeting JESD201 Class 2 whisker resistance and J-STD-020 Level 1 moisture sensitivity.
Thermally, it delivers 5W steady-state dissipation at 25°C with RθJC = 10°C/W to case and RθJA = 55°C/W to ambient - enabling reliable operation up to TJ = +150°C in high-density PCB layouts. It sustains 200A non-repetitive forward surge (IFSM, 8.3ms half-sine) and supports bidirectional EFT/ESD immunity per IEC 61000-4-2/4-4.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping initiates |
| VBR min/max | 86.7 V / 106 V @ IT = 1 mA - Ensures predictable turn-on across manufacturing lot and temperature |
| VC @ IPPM | 139 V @ 11.3 A - Limits downstream IC stress during 10/1000µs transients (IEC 61000-4-5) |
| PPK | 1500 W - Peak pulse power handling for short-duration surges (1ms, 25°C) |
| IR @ VWM | <1 µA - Negligible standby power loss and signal integrity impact in high-impedance circuits |
| TJ max | +150 °C - Enables under-hood automotive use with standard thermal relief design |
| Package | DO-214AB (SMC) - Industry-standard surface-mount outline with 0.210g mass and UL 94V-0 molding |
Pinout & Package
DO-214AB (SMC) package: molded plastic body with two coplanar matte tin-plated leads; cathode band omitted for bidirectional configuration (CA suffix). Polarity is non-directional - terminals are functionally interchangeable.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode/Cathode (symmetrical) | Bidirectional avalanche junction | No fixed anode/cathode; either terminal serves as input or return path for transient energy |
| Lead 1 / Lead 2 | Current conduction path | Both leads carry equal surge current magnitude in either direction; no PCB orientation dependency |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Identical VBR, VC, and IPPM in both polarities - eliminates need for polarity-aware layout or orientation verification |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect/load dump), and Pulse 3a/3b (EFT) - meets OEM automotive EMC requirements |
| Sub-1ps response time | Clamps within <1.0 ps from 0 V to VBR min - faster than most microcontroller I/O protection structures |
| Halogen-free & RoHS | Complies with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU - supports green manufacturing and export compliance |
| J-STD-020 Level 1 | No pre-bake required before reflow - compatible with standard SMT assembly lines without process modification |
Applications
| Automotive Power Rail Protection | CAN/LIN Bus Transient Suppression |
|---|---|
Use Scenario: 12V/24V battery-fed ECUs exposed to load dump (up to 120V, 400ms) and alternator ripple. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC-DC converters and LDOs. Use Value: Limits rail voltage to ≤139V during ISO 7637-2 Pulse 5a, preventing MOSFET gate oxide rupture and regulator latch-up. | Use Scenario: CAN FD nodes in vehicle body control modules subjected to ESD (±8kV contact) and coupled noise on differential bus lines. IC Role / Device Role / Timing Role: Bidirectional TVS across CANH–CANL, referenced to ground. Use Value: Clamps common-mode transients without distorting differential signaling integrity due to symmetrical VBR matching (±5% typical). |
| Industrial PLC I/O Protection | LED Driver Surge Immunity |
Use Scenario: 24V digital input cards interfacing with field sensors subject to inductive kickback from solenoid valves. IC Role / Device Role / Timing Role: Parallel-connected TVS at terminal block entry point. Use Value: Absorbs 1500W spikes (10/1000µs) without degradation, maintaining >100k-cycle reliability per IEC 61000-4-5 Level 4. | Use Scenario: Constant-current LED drivers in street lighting exposed to lightning-induced surges on AC mains input. IC Role / Device Role / Timing Role: Across bulk capacitor input stage (line-to-line and line-to-ground). Use Value: Withstands repeated 11.3A peak pulses while holding clamping voltage below 139V - protects bridge rectifier and primary-side controller. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78CA (Bourns) | Same VWM/VBR/VC specs but 600W PPK rating; SMB package (smaller footprint, higher RθJA = 75°C/W) | Limited to lower-energy transients; unsuitable for ISO 7637-2 Pulse 5a load dump | Select only when space-constrained and surge energy ≤600W |
| P6SMB78CA (ON Semiconductor) | Identical 1500W rating and DO-214AB package; VBR min = 86.7V, VC = 139V - matches SMCJ78CA within datasheet tolerance | Direct functional replacement with same thermal and mechanical behavior | Preferred for second-source assurance where Taiwan Semiconductor allocation is constrained |
Compared with SMBJ78CA, the SMCJ78CA provides 2.5× higher surge energy handling and superior thermal derating; versus P6SMB78CA, it offers identical protection performance with validated automotive qualification history and broader distributor availability.
Availability
SMCJ78CA is available at Aetrix Electronics and suitable for automotive ECU protection, industrial PLC I/O hardening, and LED driver surge immunity requiring stable component supply across multi-year production cycles.
Supply support for SMCJ78CA 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
Taiwan Semiconductor Company (TSC) is a vertically integrated Taiwanese semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs since 1979.
The SMCJ series belongs to TSC's high-power surface-mount TVS platform, engineered specifically for automotive-grade transient immunity (ISO 7637-2, ISO 16750-2) and industrial robustness under extended temperature and humidity stress.
FAQ
What does the "CA" suffix indicate in SMCJ78CA?
The "CA" suffix denotes a bidirectional configuration - meaning the SMCJ78CA functions identically in both polarities, with matched breakdown and clamping characteristics across its two terminals. This eliminates the need for polarity-aware placement on PCBs and makes it ideal for protecting differential buses like CAN or AC-coupled signal paths. Unlike unidirectional variants (e.g., SMCJ78A), the SMCJ78CA has no cathode marking band.
Does SMCJ78CA meet automotive EMC standards?
Yes, the SMCJ78CA is explicitly rated to meet ISO 7637-2 test pulses 1, 2a, 2b, 3a, and 3b - covering critical automotive transients including load dump, battery disconnection, and electrical fast transients. Its 1500W peak power rating and 139V clamping voltage ensure compliance with OEM-level requirements for 12V and 24V systems, as confirmed in Taiwan Semiconductor's official S2104 datasheet.
What is the maximum clamping voltage of SMCJ78CA and at what current?
The SMCJ78CA has a maximum clamping voltage (VC) of 139 V at a peak pulse current (IPPM) of 11.3 A, measured using the standardized 10/1000 µs double-exponential waveform per IEC 61000-4-5. This value is guaranteed across the full operating temperature range (−55°C to +150°C) and defines the upper voltage limit imposed on protected circuitry during surge events.
Can SMCJ78CA be used in place of a unidirectional TVS like SMCJ78A?
No - the SMCJ78CA is bidirectional and lacks polarity marking, whereas SMCJ78A is unidirectional with a defined cathode band. Substituting SMCJ78CA for SMCJ78A in a circuit relying on DC blocking or asymmetric clamping may cause unintended conduction or failure to clamp correctly. Always verify circuit topology: use SMCJ78CA only where symmetrical transient suppression is required.
What is the thermal resistance and how does it affect PCB layout for SMCJ78CA?
The SMCJ78CA has a junction-to-ambient thermal resistance (RθJA) of 55°C/W and junction-to-case (RθJC) of 10°C/W in the DO-214AB package. To maintain TJ ≤150°C under 1500W surge conditions, PCB copper area must provide adequate heat spreading - minimum recommended pad size is 100 mm² per lead with internal thermal vias. Reduced copper or elevated ambient temperatures require derating per Figure 2 in the datasheet.
SMCJ78CA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AB, SMC
- Series:
- SMCJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 2
- 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:
- Yes
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMCJ)
SMCJ78CA FAQ
1.How can I place an order for SMCJ78CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78CA 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 reliable?
The price and inventory of SMCJ78CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ78CA is usually 5 days.
3.What payment methods are accepted for SMCJ78CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78CA?
SMCJ78CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78CA 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?
For technical support, including SMCJ78CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78CA requirements.
6.How does Aetrix verify that SMCJ78CA is sourced from the original manufacturer or authorized distributors?
All SMCJ78CA 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 meets industry standards.
7.What is the process for return or replacement of SMCJ78CA?
All SMCJ78CA units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78CA, 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 part is unused and in its original packaging.
Return procedure for SMCJ78CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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