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Taiwan Semiconductor Corporation SMCJ78AH
- Part No.:
- SMCJ78AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ78AH.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:9,203
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Product details
Overview
SMCJ78AH from Taiwan Semiconductor is a unidirectional 1500W transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with 78V working stand-off voltage (VWM), 86.7–95.8V breakdown voltage (VBR), and 126V maximum clamping voltage (VC) at 12.5A peak impulse current. It provides AEC-Q101 qualification and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive load-dump and ESD protection in power supply rails.
For engineers reviewing the SMCJ78AH datasheet, SMCJ78AH pinout, SMCJ78AH application, or SMCJ78AH equivalent, this device is selected for high-energy transient suppression in 24V/48V industrial control systems, automotive ECUs, and telecom power interfaces where low clamping ratio (<1.62×VWM), sub-1ps response, and <1µA leakage above 10V are critical design requirements.
Technical Context
The SMCJ78AH employs a glass-passivated silicon junction optimized for fast avalanche response (<1.0ps rise time from 0V to VBR min) and stable clamping under repetitive 10/1000µs surge waveforms. Its unidirectional configuration enables asymmetric protection of DC power lines without reverse conduction during normal operation.
Thermal performance is defined by RθJC = 10°C/W and RθJA = 55°C/W, supporting continuous operation up to +150°C junction temperature. The device complies with JESD201 Class 2 whisker resistance and J-STD-020 Level 1 moisture sensitivity, enabling robust reflow assembly in automated SMT lines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins; sets safe margin above 24V/48V nominal rail voltages. |
| VBR @ IT=1mA | 86.7–95.8 V - Breakdown threshold range at 1mA test current; ensures reliable turn-on during transients while avoiding false triggering. |
| VC @ IPPM=12.5A | 126 V - Clamped voltage under 10/1000µs surge; limits downstream component stress to ≤126V during ISO 7637-2 Pulse 5a events. |
| PPK | 1500 W - Peak pulse power rating for 1ms non-repetitive surge; supports high-energy automotive load-dump immunity. |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off voltage; minimizes quiescent power loss in battery-backed or low-power systems. |
| TJ max | +150 °C - Maximum junction temperature; enables deployment in under-hood automotive environments and industrial enclosures. |
Pinout & Package
Package: DO-214AB (SMC), surface-mount, single-diode unidirectional configuration with cathode band marking. Case meets UL 94V-0 flammability rating; matte tin-plated leads comply with J-STD-002 solderability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | DC input / line side | Connected to protected power rail (e.g., 24V+); conducts only during forward surge or fault conditions. |
| Cathode | Clamp reference / ground return | Connected to system ground or low-impedance return path; defines clamping voltage relative to reference plane. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing per AEC standard. |
| ISO 7637-2 compliance | Meets Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) immunity requirements. |
| Glass passivated junction | Ensures stable VBR over lifetime and improved humidity resistance versus epoxy-passivated alternatives. |
| Fast response time | Typically <1.0 ps from 0 V to VBR min - faster than most microcontroller I/O protection circuits, enabling upstream surge capture. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial 48V DC Power Distribution |
|---|---|
Use Scenario: Protection of 24V/48V supply inputs against load-dump transients (ISO 7637-2 Pulse 5a) and alternator ripple in engine management modules. IC Role / Device Role / Timing Role: Primary clamping device on main power rail, placed directly at connector entry point before DC-DC converters. Use Value: Limits voltage excursion to ≤126V during 125V/350ms load-dump events, preventing damage to MCU, CAN transceivers, and sensor front-ends. | Use Scenario: Surge suppression on distributed 48V bus feeding PLC I/O modules, motor drives, and fieldbus gateways in factory automation. IC Role / Device Role / Timing Role: Unidirectional TVS placed at PSE (Power Sourcing Equipment) output and PD (Powered Device) input interfaces. Use Value: Withstands repeated 1500W surges per IEC 61000-4-5 Level 4, maintaining <1µA leakage to preserve system standby efficiency. |
| Telecom Base Station Power Supply | Renewable Energy Inverter DC Link |
Use Scenario: Input-stage protection for -48V DC telecom rectifiers exposed to lightning-induced surges on outdoor feeder lines. IC Role / Device Role / Timing Role: First-line defense parallel to bulk capacitance, clamping induced common-mode transients before they reach regulation circuitry. Use Value: 126V clamping voltage ensures downstream LDOs and PMICs remain within absolute maximum ratings during 10/1000µs surges up to 12.5A. | Use Scenario: DC-link overvoltage suppression in solar string inverters where PV array transients couple into 600–1000V DC buses. IC Role / Device Role / Timing Role: Secondary clamp staged after MOVs to handle fast-rising edge components missed by slower thermal devices. Use Value: Sub-1ps response captures nanosecond-scale ringing from IGBT switching, reducing voltage overshoot by ≥30% versus MOV-only solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78A | Lower PPK (600W), same VWM/VBR/VC specs, SMB package (smaller footprint, higher RθJA = 85°C/W). | Suitable for space-constrained consumer electronics but not automotive load-dump duty cycles. | Select SMBJ78A only when surge energy is ≤600W and board area is critical; verify thermal derating at TA > 70°C. |
| 1.5KE78A | Through-hole TO-204AA (DO-41), 1500W rating, identical VWM/VBR/VC, slower response (~1ns), higher IR (5µA). | Used in legacy industrial power supplies where SMT is not feasible or manual assembly required. | Choose 1.5KE78A for through-hole compatibility or cost-sensitive prototyping; avoid in AEC-Q101-compliant designs. |
Compared with SMBJ78A and 1.5KE78A, the SMCJ78AH delivers identical clamping performance in a surface-mount AEC-Q101-qualified package with superior thermal resistance (RθJA = 55°C/W vs. 85°C/W) and lower leakage (<1µA vs. 5µA), making it optimal for high-reliability automotive and industrial deployments requiring automated assembly.
Availability
SMCJ78AH is available at Aetrix Electronics and suitable for automotive ECU protection, industrial 48V power distribution, and telecom rectifier input stages requiring stable component supply across extended production lifecycles.
Supply support for SMCJ78AH 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, MOSFETs, and power management ICs.
The SMCJ series belongs to TSC's AEC-Q101-qualified transient suppression portfolio, engineered specifically for automotive and industrial power rail protection where high PPK, low clamping ratio, and process-controlled VBR tolerance are mandatory.
FAQ
What is the clamping voltage of SMCJ78AH at its rated peak pulse current?
The SMCJ78AH has a maximum clamping voltage (VC) of 126 V at 12.5 A peak impulse current (IPPM), measured under the standardized 10/1000 µs double-exponential surge waveform. This value is guaranteed across the full operating temperature range and ensures downstream components see no more than 126 V during worst-case transients. The SMCJ78AH achieves this with a clamping ratio of 1.62×VWM, reflecting high efficiency in energy diversion.
Is SMCJ78AH suitable for bidirectional transient protection?
No, the SMCJ78AH is a unidirectional TVS diode and is not rated for bidirectional operation. For symmetrical AC or dual-polarity DC protection, use the bipolar variant SMCJ78CAH (with CAH suffix), which provides matched clamping in both directions. Using SMCJ78AH in reverse-biased configurations beyond its specified VWM may cause permanent junction degradation or premature failure.
Does SMCJ78AH meet automotive qualification standards?
Yes, the SMCJ78AH is explicitly AEC-Q101 qualified and tested per the full stress-test schedule including HTGB, H3TRB, TC, and ESD. It also meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b requirements for automotive electrical disturbances. These qualifications are documented in Taiwan Semiconductor's official A2102 datasheet revision and apply specifically to the SMCJ78AH part number.
What is the maximum steady-state power dissipation for SMCJ78AH?
The SMCJ78AH has a steady-state power dissipation (PD) rating of 5 W at TA = 25°C, as specified in its Absolute Maximum Ratings table. This value applies only to continuous DC or low-frequency reverse-bias conditions-not surge events. In normal operation, reverse leakage remains below 1 µA above 10 V, resulting in negligible steady-state power loss. The 5 W rating supports short-term thermal overload handling during infrequent transients.
How does the SMCJ78AH compare to SMCJ78H in terms of breakdown voltage tolerance?
The SMCJ78AH has a tighter VBR tolerance: 86.7–95.8 V (min–max) at IT = 1 mA, versus SMCJ78H's wider 86.7–106 V range. This narrower spread improves design predictability in high-precision clamping applications, such as protecting 75–80 V-rated DC-DC controllers where excessive VBR variation could compromise margin. Both share identical VWM (78 V), VC (126 V / 139 V), and PPK (1500 W) ratings.
SMCJ78AH 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:
- 1
- Bidirectional Channels:
- -
- 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)
SMCJ78AH FAQ
1.How can I place an order for SMCJ78AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ78AH 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 SMCJ78AH reliable?
The price and inventory of SMCJ78AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ78AH is usually 5 days.
3.What payment methods are accepted for SMCJ78AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ78AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ78AH?
SMCJ78AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ78AH 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 SMCJ78AH?
For technical support, including SMCJ78AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ78AH requirements.
6.How does Aetrix verify that SMCJ78AH is sourced from the original manufacturer or authorized distributors?
All SMCJ78AH 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 SMCJ78AH meets industry standards.
7.What is the process for return or replacement of SMCJ78AH?
All SMCJ78AH units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ78AH, 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 SMCJ78AH part is unused and in its original packaging.
Return procedure for SMCJ78AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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