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Taiwan Semiconductor Corporation SMCJ78CAH
- Part No.:
- SMCJ78CAH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78CAH.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:7,590
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Product details
Overview
SMCJ78CAH from Taiwan Semiconductor is a bidirectional 1500W transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, designed for high-energy surge protection in automotive and industrial power lines. It features a 78V working stand-off voltage (VWM), 86.7–95.8V breakdown voltage (VBR), 12.5A peak impulse current (IPPM), and clamps transients to ≤126V at rated surge. Used in 12/24V DC systems subject to ISO 7637-2 Pulse 1/2a/2b/3a/3b.
For engineers reviewing the SMCJ78CAH datasheet, SMCJ78CAH pinout, SMCJ78CAH application, or SMCJ78CAH equivalent, this page delivers verified electrical specs, AEC-Q101 qualification status, bidirectional clamping behavior, thermal resistance (RθJC = 10°C/W), and direct comparison with industry-standard alternatives for automotive ESD and load-dump protection.
Technical Context
The SMCJ78CAH is a glass-passivated, bipolar junction TVS diode optimized for fast response (<1.0 ps rise time from 0 V to VBR min) and low leakage (<1 µA @ 78 V). Its bidirectional configuration enables symmetrical clamping in AC-coupled or floating bus applications without polarity constraints.
It meets ISO 7637-2 immunity requirements for automotive electronics and supports steady-state power dissipation of 5 W at 25°C with junction temperature range from –55°C to +150°C. Thermal performance is defined by RθJA = 55°C/W and RθJC = 10°C/W, enabling reliable operation under pulsed surge conditions in compact PCB layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins; sets system-level overvoltage trip threshold. |
| VBR (min/max) | 86.7 V / 95.8 V - Breakdown occurs within this range at 1 mA test current; defines minimum clamping onset point. |
| VC @ IPPM | ≤126 V - Clamped voltage at 12.5 A peak impulse (10/1000 µs waveform); determines maximum stress on downstream ICs. |
| PPK | 1500 W - Peak pulse power handling capability; validates suitability for ISO 7637-2 Pulse 5a (load dump) events. |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off voltage; ensures minimal quiescent power loss in always-on circuits. |
| TJ max | +150 °C - Maximum junction temperature rating; supports under-hood automotive deployment with thermal margin. |
| RθJC | 10 °C/W - Junction-to-case thermal resistance; enables effective heatsinking via PCB copper pour or metal-core substrate. |
Pinout & Package
Package: DO-214AB (SMC), surface-mount, bidirectional device with cathode band omitted (no polarity marking required).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode/Cathode (symmetrical) | Bidirectional surge path | Either terminal serves as anode or cathode depending on transient polarity; no orientation required during placement. |
| Case (cathode band absent) | Thermal and mechanical interface | Exposed metal slug provides primary thermal conduction path to PCB; requires soldered thermal pad per JEDEC MO-215. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HAST, and mechanical shock per JESD22 standards. |
| Glass passivated junction | Enhances long-term stability and moisture resistance vs. epoxy-passivated alternatives; critical for under-hood longevity. |
| ISO 7637-2 compliance | Tested against Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) waveforms. |
| Fast response time | <1.0 ps from 0 V to VBR min - limits voltage overshoot during nanosecond-scale ESD events (IEC 61000-4-2). |
| Halogen-free & RoHS | Complies with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU; suitable for green manufacturing and export compliance. |
Applications
| Automotive Power Distribution | Industrial PLC I/O Protection |
|---|---|
|
Use Scenario: Protecting 24V CAN bus power rails and sensor supply lines in engine control units (ECUs) against load dump and alternator ripple. IC Role / Device Role / Timing Role: Bidirectional clamping element placed upstream of LDOs and CAN transceivers to limit transient excursions below 126 V. Use Value: Enables robust operation under ISO 7637-2 Pulse 5a (load dump up to 60 V × 400 ms) without derating or parallel devices. |
Use Scenario: Safeguarding digital input modules in programmable logic controllers exposed to inductive kickback from solenoid valves and contactors. IC Role / Device Role / Timing Role: Standoff protector across 24V DC inputs, absorbing repetitive 1500W surges while maintaining <1 µA leakage at nominal voltage. Use Value: Eliminates need for external series impedance or RC snubbers due to sub-ns response and stable VBR tolerance (±5.5%). |
| Telecom DC Feeds | Renewable Energy Controllers |
|
Use Scenario: Shielding remote radio head (RRH) power inputs from lightning-induced surges on outdoor telecom cabinet DC feeds. IC Role / Device Role / Timing Role: Primary surge arrestor in multi-stage protection scheme, clamping fast-rising transients before MOV-based secondary stage. Use Value: Delivers consistent 126 V clamping across –40°C to +125°C ambient, supporting extended outdoor temperature ranges. |
Use Scenario: Securing battery management system (BMS) voltage monitoring lines in solar charge controllers subjected to PV array switching transients. IC Role / Device Role / Timing Role: Bidirectional clamp on 72V nominal battery sense lines, preventing false overvoltage trips during MOSFET commutation. Use Value: Maintains 78 V stand-off with zero polarity sensitivity-critical for floating differential measurements in ungrounded PV topologies. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78CA | Lower PPK (600 W), same VWM/VBR range, SMB package (smaller footprint, higher RθJA = 85°C/W) | Limited to lower-energy transients (e.g., IEC 61000-4-5 Level 3); unsuitable for ISO 7637-2 Pulse 5a. | Select SMBJ78CA only when space-constrained and surge energy is ≤600 W; verify thermal margin with RθJA derating. |
| 1.5KE78CA | Higher PPK (1500 W), axial-leaded DO-201 package, slower response (~1 ns), higher IR (5 µA @ 78 V) | Requires through-hole mounting; less suitable for automated SMT lines and high-frequency ESD events. | Choose 1.5KE78CA for legacy through-hole designs or cost-sensitive non-automotive applications where AEC-Q101 is not required. |
Compared with SMBJ78CA and 1.5KE78CA, the SMCJ78CAH offers superior thermal performance (RθJC = 10°C/W), AEC-Q101 qualification, and faster response-making it the preferred choice for automotive SMT designs requiring full ISO 7637-2 compliance and high-reliability surge immunity.
Availability
SMCJ78CAH is available at Aetrix Electronics and suitable for automotive ECUs, industrial PLCs, telecom power feeds, and renewable energy controllers requiring stable component supply with AEC-Q101 assurance and full ISO 7637-2 validation.
Supply support for SMCJ78CAH 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 Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and power MOSFETs for automotive and industrial markets.
The SMCJ78CAH belongs to TSC's AEC-Q101-qualified SMCJ(A)H family, engineered specifically for high-energy transient suppression in harsh-environment automotive power networks and industrial control systems.
FAQ
What does the "CAH" suffix indicate in SMCJ78CAH?
The "CAH" suffix denotes a bidirectional configuration with AEC-Q101 qualification and halogen-free construction. Unlike unidirectional "H" variants, SMCJ78CAH provides symmetrical clamping in both polarities-ideal for AC-coupled or floating bus protection without polarity concerns. This matches the exact marking and specification listed in TSC's official datasheet revision A2102.
Is SMCJ78CAH compliant with ISO 7637-2, and which pulses does it cover?
Yes, SMCJ78CAH is explicitly validated for ISO 7637-2 Pulse 1 (inductive switch-off), Pulse 2a/2b (supply line transients), and Pulse 3a/3b (capacitive coupling). Its 1500W peak power rating and ≤126V clamping voltage ensure compliance with all five standard test waveforms-confirmed in TSC's application notes and test reports for the SMCJ(A)H series.
What is the maximum clamping voltage (VC) of SMCJ78CAH at its rated surge current?
The maximum clamping voltage VC of SMCJ78CAH is 126 V at 12.5 A peak impulse current (IPPM), measured using the standardized 10/1000 µs double-exponential waveform per Fig.5 in the datasheet. 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.
How does SMCJ78CAH differ from SMCJ78AH in terms of electrical performance?
SMCJ78CAH is bidirectional, while SMCJ78AH is unidirectional. Their key differences include: SMCJ78CAH has identical VBR (86.7–95.8 V) and VC (126 V) in both directions, whereas SMCJ78AH only clamps in reverse and conducts forward at ~3.5 V. Also, SMCJ78CAH omits the cathode band marking-critical for correct placement verification in automated assembly.
What thermal design considerations apply to SMCJ78CAH in high-power surge scenarios?
SMCJ78CAH has RθJC = 10°C/W and RθJA = 55°C/W. For repeated 1500W surges, thermal relief requires ≥100 mm² of 2-oz copper connected to the cathode pad, plus optional thermal vias to inner ground planes. Derating curves (Fig.2) show >50% power reduction above 75°C ambient-so board layout must prioritize heat spreading, not just trace width.
SMCJ78CAH 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:
- 1
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 12.5A
- Power - Peak Pulse:
- 1500W (1.5kW)
- Power Line Protection:
- No
- Applications:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMC)
SMCJ78CAH FAQ
1.How can I place an order for SMCJ78CAH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78CAH 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 SMCJ78CAH reliable?
The price and inventory of SMCJ78CAH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ78CAH is usually 5 days.
3.What payment methods are accepted for SMCJ78CAH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78CAH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78CAH?
SMCJ78CAH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78CAH 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 SMCJ78CAH?
For technical support, including SMCJ78CAH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78CAH requirements.
6.How does Aetrix verify that SMCJ78CAH is sourced from the original manufacturer or authorized distributors?
All SMCJ78CAH 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 SMCJ78CAH meets industry standards.
7.What is the process for return or replacement of SMCJ78CAH?
All SMCJ78CAH units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78CAH, 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 SMCJ78CAH part is unused and in its original packaging.
Return procedure for SMCJ78CAH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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