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Taiwan Semiconductor Corporation SMBJ78AH
- Part No.:
- SMBJ78AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ78AH.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AA
- Quantity:
- Payment:
- Shipping:
Inventory:2,767
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Product details
Overview
SMBJ78AH from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AA (SMB) package, rated for 600W peak pulse power, 78V working stand-off voltage (VWM), and 126V maximum clamping voltage (VC) at 5.0A peak impulse current - designed for automotive-grade ESD and load-dump protection in power supply rails and interface lines.
For engineers reviewing the SMBJ78AH datasheet, SMBJ78AH pinout, SMBJ78AH application, or SMBJ78AH equivalent, key selection criteria include its AEC-Q101 qualification, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, <1.0ps response time, <1μA leakage above 10V, and DO-214AA mechanical compatibility with automated SMT assembly.
Technical Context
The SMBJ78AH operates as a unidirectional avalanche diode, triggering when reverse voltage exceeds its 86.7–95.8V breakdown range (VBR @ IT = 1mA). It clamps transients to ≤126V at 5.0A (10/1000µs waveform), with thermal resistance RθJA = 55°C/W and RθJC = 10°C/W, enabling reliable operation up to +150°C junction temperature.
Its glass-passivated junction ensures stable VBR tolerance and low leakage (<1µA @ VWM), while the matte tin-plated leads meet J-STD-002 solderability and JESD201 Class 2 whisker resistance - critical for long-term reliability in automotive and industrial control modules.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 86.7 / 95.8 V @ 1 mA - Confirmed breakdown threshold range for reliable turn-on margin |
| VC @ IPP | 126 V @ 5.0 A (10/1000µs) - Peak clamped voltage limiting downstream IC stress during surge events |
| PPK | 600 W - Peak pulse power handling per single transient, derated above 25°C ambient |
| ID @ VWM | <1 µA - Minimal leakage current preserving signal integrity and battery drain in always-on circuits |
| TJ max | +150 °C - Maximum junction temperature supporting under-hood automotive deployment |
| Package | DO-214AA (SMB) - Standardized 2-pin surface-mount outline with 0.090g mass and UL 94V-0 molding |
Pinout & Package
DO-214AA (SMB) package: cathode-banded, 2-terminal unidirectional configuration; body length 4.57 mm, width 3.94 mm, height 2.29 mm; matte tin-plated leads, polarity marked by band on cathode end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path) in unidirectional TVS orientation |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 78V rail); conducts only during overvoltage transients |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronics per stress test requirements including HTOL, TC, UHAST, and ESD |
| ISO 7637-2 compliant | Withstands Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (line impedance coupling) |
| Fast response time | <1.0 ps - Limits voltage overshoot before protection engages, critical for high-speed data lines |
| Glass passivated junction | Ensures stable VBR over lifetime and improved humidity resistance vs. epoxy-passivated alternatives |
| Moisture sensitivity level 1 | No floor life limitation or bake requirement prior to reflow - simplifies SMT manufacturing flow |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 78V auxiliary power bus in ADAS domain controllers from load-dump spikes and alternator surges. IC Role / Device Role / Timing Role: Unidirectional TVS placed between rail and chassis ground to clamp transients below 126V. Use Value: Prevents latch-up or permanent damage to PMICs and microcontrollers rated for ≤130V absolute max. | Use Scenario: Safeguarding RS-485 transceivers in factory automation I/O modules against EFT and ESD events. IC Role / Device Role / Timing Role: Connected across differential pair (A/B) and ground to suppress common-mode transients without distorting signal integrity. Use Value: Maintains >1 Mbps data rate stability under IEC 61000-4-4 Level 4 (4 kV) fast transient bursts. |
| LED Driver Overvoltage Clamping | DC-DC Converter Input Stage Protection |
Use Scenario: Shielding constant-current LED drivers in commercial lighting systems from inductive switching spikes. IC Role / Device Role / Timing Role: Mounted across driver input terminals to absorb energy from relay coil flyback or transformer leakage. Use Value: Enables use of cost-effective non-automotive-grade drivers by limiting input voltage excursions to ≤126V. | Use Scenario: Front-end protection for 78V-input buck converters in telecom power supplies subjected to lightning-induced surges. IC Role / Device Role / Timing Role: Placed upstream of input filter capacitor to divert surge current before reaching controller IC and MOSFETs. Use Value: Extends converter MTBF by preventing gate oxide rupture and bootstrap capacitor overvoltage failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78A | Non-AEC-Q101; same VWM/VBR/VC specs but lacks automotive qualification and ISO 7637-2 validation | Acceptable for industrial/commercial use only; not suitable for automotive ECUs or ADAS modules | Select SMBJ78A only if automotive compliance is not required and cost is prioritized over qualification rigor |
| SAC78 | Same DO-214AA package; lower PPK (400W), higher VC (137V @ 4.5A), no AEC-Q101 or ISO 7637-2 documentation | Limited to less severe surge environments; insufficient for full ISO 7637-2 Pulse 1 testing | Choose SAC78 only for space-constrained consumer applications where 600W rating is not mandated |
Compared with SMBJ78AH, SMBJ78A omits automotive qualification and system-level immunity validation, while SAC78 trades peak power and clamping performance for lower cost - making SMBJ78AH the sole choice for AEC-Q101-compliant 78V rail protection requiring full ISO 7637-2 coverage.
Availability
SMBJ78AH is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor interfaces, LED driver designs, and DC-DC converter input stages requiring stable component supply with full AEC-Q101 traceability and ISO 7637-2 compliance.
Supply support for SMBJ78AH 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 automotive-qualified components since 1979.
The SMBJH series was developed specifically for automotive and industrial transient suppression, emphasizing AEC-Q101 reliability, ISO 7637-2 immunity, and robust SMT manufacturability in DO-214AA packaging.
FAQ
What is the breakdown voltage range of SMBJ78AH?
The SMBJ78AH has a minimum breakdown voltage (VBR) of 86.7 V and a maximum of 95.8 V, measured at 1 mA test current (IT). This range ensures consistent clamping behavior across production lots while providing sufficient margin above its 78 V working stand-off voltage to avoid false triggering during normal operation.
Is SMBJ78AH suitable for bidirectional transient protection?
No, SMBJ78AH is a unidirectional TVS diode and must be used with correct polarity - cathode connected to the protected line, anode to ground. For bidirectional protection, select SMBJ78ACH (with CH suffix) or SMBJ78CAH (with CAH suffix), which feature symmetrical breakdown in both directions.
Does SMBJ78AH meet automotive qualification standards?
Yes, SMBJ78AH is AEC-Q101 qualified and explicitly validated for ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b waveforms. Its glass-passivated junction, JESD201 Class 2 whisker resistance, and moisture sensitivity level 1 further support automotive under-hood and chassis-mounted applications.
What is the maximum clamping voltage of SMBJ78AH under surge conditions?
The SMBJ78AH clamps to a maximum of 126 V when subjected to a 5.0 A peak impulse current with a 10/1000 µs waveform. This value defines the highest voltage seen by downstream circuitry during standardized surge events and is critical for ensuring compatibility with 130 V-rated ICs and capacitors.
Can SMBJ78AH be used in high-temperature environments?
Yes, SMBJ78AH supports continuous operation up to +150°C junction temperature (TJ), with thermal resistance RθJA = 55°C/W. When mounted on standard 1 oz copper PCB with recommended pad layout, it maintains safe thermal margins in engine control units and power distribution modules exposed to elevated ambient temperatures.
SMBJ78AH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJH
- 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):
- 5A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AA (SMB)
SMBJ78AH FAQ
1.How can I place an order for SMBJ78AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ78AH 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 SMBJ78AH reliable?
The price and inventory of SMBJ78AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ78AH is usually 5 days.
3.What payment methods are accepted for SMBJ78AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ78AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ78AH?
SMBJ78AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ78AH 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 SMBJ78AH?
For technical support, including SMBJ78AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ78AH requirements.
6.How does Aetrix verify that SMBJ78AH is sourced from the original manufacturer or authorized distributors?
All SMBJ78AH 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 SMBJ78AH meets industry standards.
7.What is the process for return or replacement of SMBJ78AH?
All SMBJ78AH units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ78AH, 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 SMBJ78AH part is unused and in its original packaging.
Return procedure for SMBJ78AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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