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Taiwan Semiconductor Corporation SMDJ78AH
- Part No.:
- SMDJ78AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMDJ78AH.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AB
- Quantity:
- Payment:
- Shipping:
Inventory:7,957
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Product details
Overview
SMDJ78AH from Taiwan Semiconductor is a unidirectional 3000W surface-mount transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with a working stand-off voltage of 78 V, breakdown voltage range of 86.7–95.8 V at 1 mA, and clamping voltage of 126 V at 23.8 A peak pulse current. It is AEC-Q101 qualified and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive load-dump and switching transient protection.
For engineers reviewing the SMDJ78AH datasheet, SMDJ78AH pinout, SMDJ78AH application, or SMDJ78AH equivalent, key selection criteria include its 3000 W peak pulse power rating, 126 V clamping performance at 23.8 A, DO-214AB thermal resistance (RθJA = 75 °C/W), AEC-Q101 qualification, and compliance with ISO 7637-2 for automotive electronics robustness.
Technical Context
The SMDJ78AH operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology for stable breakdown and fast response (<1.0 ps). Its clamping behavior is defined by a 10/1000 µs waveform per R.E.A., with peak pulse current limited by thermal derating above 25 °C per Fig.2.
Designed for high-energy transients, it delivers 3000 W peak power at TA = 25 °C, with steady-state dissipation of 6.5 W and junction temperature range from –55 °C to +175 °C. It supports automated placement and meets JESD201 Class 2 whisker resistance and J-STD-020 Level 1 moisture sensitivity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR @ IT=1 mA | 86.7–95.8 V - Verified avalanche breakdown threshold under standardized test current |
| VC @ IPPM=23.8 A | 126 V - Clamped voltage during 10/1000 µs transient, limiting downstream stress |
| PPK | 3000 W - Peak pulse power handling capability at TA = 25 °C, critical for load-dump immunity |
| RθJA | 75 °C/W - Junction-to-ambient thermal resistance, defining PCB heatsinking requirements |
| IFSM | 300 A - 8.3 ms single half-sine surge current rating, supporting high-energy inductive kick events |
| TJ Range | –55 °C to +175 °C - Extended operational junction temperature range for under-hood automotive use |
Pinout & Package
DO-214AB (SMC) surface-mount package with matte tin-plated leads, polarity indicated by cathode band. Weight: 0.290 g. UL 94V-0 compliant molding compound.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to system ground or low-side return path in unidirectional TVS configuration |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 12 V rail); conducts during overvoltage to clamp to 126 V |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated reliability for automotive powertrain and body electronics per stress-test requirements |
| Glass passivated junction | Enhanced long-term stability and leakage control under thermal cycling and humidity |
| ISO 7637-2 compliance | Proven immunity to Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect/load dump), and Pulse 3a/3b (switching noise) |
| Fast response time <1.0 ps | Enables suppression of nanosecond-scale ESD and fast-rising transients before IC damage occurs |
| J-STD-020 Level 1 moisture sensitivity | Allows unlimited floor life and reflow without baking, simplifying SMT manufacturing |
Applications
| Automotive Power Distribution | Industrial DC Power Input |
|---|---|
Use Scenario: Protection of 12 V/24 V battery-fed ECUs against load-dump transients up to ±120 V per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp surges before LDOs or MCUs. Use Value: Limits peak voltage to 126 V at 23.8 A, preventing damage to 36 V-rated input stages in automotive microcontrollers. | Use Scenario: Guarding programmable logic controller (PLC) 24 V DC inputs against field-wiring induced transients and relay coil flyback. IC Role / Device Role / Timing Role: Primary overvoltage clamp on industrial power entry, coordinated with upstream fuses and downstream TVS arrays. Use Value: Withstands 3000 W pulses and maintains <1 µA leakage at 78 V, ensuring no false triggering during normal operation. |
| Telecom Power Interface | Consumer Equipment DC Adapter Input |
Use Scenario: Safeguarding PoE-powered network switches and base stations from lightning-induced surges on 48 V DC supply lines. IC Role / Device Role / Timing Role: First-line transient suppressor before DC-DC converters and Ethernet PHY power rails. Use Value: Clamps 10/1000 µs transients to ≤126 V while maintaining low capacitance, avoiding signal integrity degradation on adjacent data lines. | Use Scenario: Protecting USB-C PD adapters and smart home hubs from AC/DC adapter output overshoot and hot-plug transients. IC Role / Device Role / Timing Role: Secondary-level TVS on secondary-side DC bus, after isolation transformer and rectifier. Use Value: AEC-Q101 qualification and halogen-free construction support safety certifications (UL/EN 62368-1) and RoHS compliance for consumer end-products. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SAC78 | Lower peak power (1500 W), higher clamping voltage (135 V @ 15 A), same DO-214AB package | Not rated for ISO 7637-2 Pulse 5a; suitable only for lower-energy consumer-grade transients | Select SMDJ78AH when 3000 W surge immunity and automotive qualification are required. |
| SMCJ78A | Identical electrical specs and package; manufactured by Vishay, not AEC-Q101 qualified | Lacks automotive qualification; may require additional validation for automotive Tier-1 designs | Choose SMDJ78AH where AEC-Q101 compliance and ISO 7637-2 certification are mandatory. |
Compared with SAC78 and SMCJ78A, the SMDJ78AH uniquely combines 3000 W peak power, 126 V clamping, AEC-Q101 qualification, and full ISO 7637-2 Pulse 1/2a/2b/3a/3b coverage-making it the preferred choice for automotive and industrial systems demanding validated transient robustness.
Availability
SMDJ78AH is available at Aetrix Electronics and suitable for automotive ECUs, industrial PLCs, and telecom power interfaces requiring stable component supply, AEC-Q101 assurance, and ISO 7637-2 compliance.
Supply support for SMDJ78AH 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, and rectifiers, with global distribution and AEC-Q101-compliant production lines.
The SMDJ78AH belongs to TSC's SMDJxH series of high-power unidirectional TVS diodes, engineered specifically for automotive and industrial applications where robust load-dump and switching transient immunity is non-negotiable.
FAQ
What is the clamping voltage of the SMDJ78AH under standard test conditions?
The SMDJ78AH has a maximum clamping voltage (VC) of 126 V when subjected to a 10/1000 µs peak pulse current of 23.8 A. This value is measured per standard R.E.A. waveform definition and ensures predictable overvoltage limiting for downstream circuitry. The SMDJ78AH achieves this clamping performance while maintaining low leakage (<1 µA at 78 V) and fast response (<1.0 ps), making it suitable for protecting sensitive automotive and industrial electronics.
Is the SMDJ78AH suitable for bidirectional transient suppression?
No, the SMDJ78AH is a unidirectional TVS diode and is not rated for bidirectional operation. For bidirectional applications in the same voltage range, Taiwan Semiconductor offers the SMDJ78CAH variant (marked DGT), which provides symmetrical clamping in both polarities. Using the SMDJ78AH in reverse-biased configurations beyond its specified ratings risks permanent junction damage. Always verify polarity alignment during PCB layout for the SMDJ78AH.
Does the SMDJ78AH meet automotive qualification standards?
Yes, the SMDJ78AH is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b requirements. These qualifications validate its suitability for automotive power networks-including engine control units, body control modules, and infotainment systems-where exposure to load-dump, battery disconnect, and inductive switching transients is routine. The SMDJ78AH's 175 °C maximum junction temperature further supports under-hood deployment.
What is the thermal resistance and how does it affect PCB layout for the SMDJ78AH?
The SMDJ78AH has a junction-to-ambient thermal resistance (RθJA) of 75 °C/W and junction-to-lead resistance (RθJL) of 15 °C/W. To maintain safe operation during repetitive 3000 W pulses, PCB copper area must be optimized-typically ≥100 mm² of 2 oz copper per pad connected via multiple thermal vias to internal ground planes. The SMDJ78AH's DO-214AB package requires adherence to TSC's suggested pad layout to ensure reliable solder joint integrity and thermal performance.
How does the SMDJ78AH compare to the SMDJ75AH in terms of voltage ratings and application fit?
The SMDJ78AH has a 78 V working stand-off voltage (VWM) and 86.7–95.8 V breakdown range, versus the SMDJ75AH's 75 V VWM and 83.3–92.1 V VBR. This 3 V higher stand-off allows the SMDJ78AH to better tolerate nominal 24 V system tolerances (e.g., 28.5 V max charging) without leakage or premature clamping. Both share identical 3000 W rating and DO-214AB packaging, but the SMDJ78AH is preferred where tighter margin against sustained overvoltage is needed-such as in commercial vehicle 24 V architectures.
SMDJ78AH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AB, SMC
- Series:
- SMDJ
- 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):
- 23.8A
- Power - Peak Pulse:
- 3000W (3kW)
- Power Line Protection:
- No
- Applications:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMC)
SMDJ78AH FAQ
1.How can I place an order for SMDJ78AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMDJ78AH 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 SMDJ78AH reliable?
The price and inventory of SMDJ78AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMDJ78AH is usually 5 days.
3.What payment methods are accepted for SMDJ78AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMDJ78AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMDJ78AH?
SMDJ78AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMDJ78AH 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 SMDJ78AH?
For technical support, including SMDJ78AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMDJ78AH requirements.
6.How does Aetrix verify that SMDJ78AH is sourced from the original manufacturer or authorized distributors?
All SMDJ78AH 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 SMDJ78AH meets industry standards.
7.What is the process for return or replacement of SMDJ78AH?
All SMDJ78AH units undergo pre-shipment inspection (PSI). If there is an issue with SMDJ78AH, 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 SMDJ78AH part is unused and in its original packaging.
Return procedure for SMDJ78AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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