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Taiwan Semiconductor Corporation SMBJ78C
- Part No.:
- SMBJ78C
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ78C.pdf
- Description:
- 600W, 96.4V, 10%, BIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:4,651
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Product details
Overview
SMBJ78C from Taiwan Semiconductor is a unidirectional transient voltage suppressor diode (TVS) in DO-214AA (SMB) package, designed for high-energy surge protection in DC power rails and signal lines. It features a 78 V working stand-off voltage (VWM), 86.7–106 V breakdown voltage (VBR), 139 V maximum clamping voltage (VC) at 4.5 A peak impulse current (IPP), and 600 W peak pulse power rating - ideal for automotive load-dump and industrial I/O port protection.
For engineers reviewing the SMBJ78C datasheet, SMBJ78C pinout, SMBJ78C application, or SMBJ78C equivalent, key selection criteria include clamping performance under 10/1000 µs transients, low leakage (<1 µA above 10 V), compliance with ISO 7637-2 Pulse 1/2a/2b/3a/3b, and thermal robustness up to 150 °C junction temperature.
Technical Context
The SMBJ78C employs a glass-passivated silicon junction optimized for fast response (<1.0 ps) and stable clamping across temperature. Its unidirectional configuration provides forward conduction only during reverse overvoltage events, with VF = 3.5 V @ 50 A for devices ≤90 V - confirmed for SMBJ78C per datasheet Note 2.
Thermal design is supported by RθJC = 10 °C/W and RθJA = 55 °C/W, enabling reliable operation at TA = 25 °C with derating above ambient. The device meets JESD201 Class 2 whisker resistance and J-STD-020 Moisture Sensitivity Level 1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous DC or RMS voltage the device blocks without clamping |
| VBR min/max | 86.7 V / 106 V @ IT = 1 mA - ensures reliable triggering above normal operating voltage with margin |
| VC @ IPP | 139 V @ IPP = 4.5 A (10/1000 µs) - defines worst-case voltage seen by protected circuit during surge |
| PPK | 600 W - peak non-repetitive surge energy handling capability per single transient event |
| ID @ VWM | <1 µA - negligible leakage current preserves system efficiency and signal integrity |
| TJ max | +150 °C - enables use in under-hood automotive and high-temperature industrial environments |
Pinout & Package
DO-214AA (SMB) surface-mount package: cathode-banded end denotes polarity; matte tin-plated leads compliant with J-STD-002 solderability; UL 94V-0 molding compound; weight ≈ 0.090 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side connection point | Connected to ground or low-voltage reference; completes clamping path during reverse surge |
| Cathode | High-side connection point | Connected to protected line (e.g., 24 V rail); blocks forward current, conducts reverse surge to ground |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR over lifetime and improved reliability vs. epoxy-passivated alternatives |
| ISO 7637-2 compliance | Validated for automotive electrical disturbance immunity (Pulse 1/2a/2b/3a/3b), reducing qualification risk |
| Fast response time <1.0 ps | Clamps transients before sensitive downstream ICs experience overstress |
| RoHS & halogen-free | Meets IEC 61249-2-21 and global environmental regulations for industrial and automotive PCBs |
Applications
| Automotive Power Rail Protection | Industrial PLC I/O Protection |
|---|---|
Use Scenario: Protecting 24 V supply lines in vehicle body control modules against load dump and alternator spikes. IC Role / Device Role: Unidirectional TVS placed between power rail and chassis ground to clamp surges exceeding 78 V. Use Value: Limits transient voltage to ≤139 V, preventing damage to microcontrollers and CAN transceivers rated for 36 V absolute max. | Use Scenario: Safeguarding analog input channels of programmable logic controllers exposed to field wiring transients. IC Role / Device Role: Front-end TVS on 0–10 V or 4–20 mA sensor inputs to absorb EFT and inductive kickback. Use Value: Maintains signal integrity with <1 µA leakage at 78 V, avoiding measurement drift in precision acquisition circuits. |
| LED Driver Overvoltage Clamp | DC Motor Control Board Surge Suppression |
Use Scenario: Preventing catastrophic failure of constant-current LED drivers subjected to 100 V+ surges during hot-swap events. IC Role / Device Role: Parallel-connected TVS across driver output to shunt excess energy during overvoltage faults. Use Value: 600 W PPK rating handles repetitive switching surges without degradation; DO-214AA footprint supports automated placement. | Use Scenario: Shielding H-bridge gate drivers and current sense amplifiers from back-EMF spikes generated by brushed DC motors. IC Role / Device Role: Bidirectional-capable variant (SMBJ78CA) used across motor terminals; SMBJ78C applied on low-side sensing path. Use Value: Clamps 10/1000 µs transients to 139 V within 1 ps, protecting 5 V logic interfaces tied to motor control ICs. |
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 | Narrower VBR range (86.7–95.8 V) and lower VC = 126 V @ 5.0 A IPP; same VWM and PPK | Better clamping performance for systems requiring tighter voltage margin below 130 V | Select SMBJ78A when lower clamping voltage is critical and peak surge current exceeds 4.5 A |
| SMCJ78C | Same VWM/VBR/VC specs but in larger DO-214AB (SMC) package; higher PPK = 1500 W | Used where higher surge energy (e.g., ISO 7637-2 Pulse 5a) or thermal mass is required | Choose SMCJ78C for enhanced ruggedness in high-reliability automotive ECUs with space for larger footprint |
Compared with SMBJ78A and SMCJ78C, SMBJ78C offers balanced clamping (139 V), compact SMB packaging, and verified ISO 7637-2 compliance - making it optimal for space-constrained 24 V systems needing 600 W surge handling without layout redesign.
Availability
SMBJ78C is available at Aetrix Electronics and suitable for automotive infotainment power supplies, industrial sensor interface modules, and LED lighting drivers requiring stable component supply and full traceability.
Supply support for SMBJ78C 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, rectifiers, and MOSFETs, with ISO/TS 16949 and ISO 14001 certifications.
The SMBJ series was developed specifically for high-reliability transient suppression in automotive and industrial environments, emphasizing ISO 7637-2 compliance, tight parametric distribution, and robust thermal performance in surface-mount packages.
FAQ
What is the maximum clamping voltage of SMBJ78C under standard 10/1000 µs surge conditions?
The SMBJ78C has a maximum clamping voltage (VC) of 139 V when subjected to a 4.5 A peak impulse current with a 10/1000 µs waveform. This value is measured per ANSI/IEEE C62.35 and defines the upper voltage limit imposed on protected circuitry during surge events - critical for ensuring downstream components remain within their absolute maximum ratings.
Is SMBJ78C suitable for bidirectional transient protection?
No, SMBJ78C is a unidirectional TVS diode intended for DC line protection where polarity is fixed. For bidirectional applications such as AC lines or differential data buses, the SMBJ78CA variant must be used - it features symmetrical breakdown in both directions and identical VWM/VBR/VC specifications.
Does SMBJ78C meet automotive electromagnetic compatibility standards?
Yes, SMBJ78C meets ISO 7637-2 requirements for electrical disturbances on automotive 12 V and 24 V systems, covering Pulse 1 (inductive load disconnect), Pulse 2a/2b (load dump simulation), and Pulse 3a/3b (capacitive coupling). This validation is explicitly stated in the official Taiwan Semiconductor datasheet Version R2104.
What is the thermal resistance from junction to ambient for SMBJ78C?
The SMBJ78C has a junction-to-ambient thermal resistance (RθJA) of 55 °C/W under standard JEDEC test conditions (single device on 1 in² FR-4 board with 2 oz copper). This value enables accurate thermal modeling for PCB layout - especially important when operating near its 150 °C maximum junction temperature in enclosed enclosures.
How does SMBJ78C differ from SMBJ78A in practical circuit protection?
SMBJ78C clamps at 139 V @ 4.5 A, while SMBJ78A clamps at 126 V @ 5.0 A - offering tighter voltage control for systems with narrow operating margins. Both share identical 78 V VWM and 600 W PPK, but SMBJ78A's lower VC improves protection for 3.3 V or 5 V logic interfaces downstream of the TVS, provided surge current remains ≥5.0 A.
SMBJ78C Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJ
- 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:
- 139V
- Current - Peak Pulse (10/1000µs):
- 4.5A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AA (SMB)
SMBJ78C FAQ
1.How can I place an order for SMBJ78C through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ78C 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 SMBJ78C reliable?
The price and inventory of SMBJ78C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ78C is usually 5 days.
3.What payment methods are accepted for SMBJ78C?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ78C transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ78C?
SMBJ78C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ78C 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 SMBJ78C?
For technical support, including SMBJ78C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ78C requirements.
6.How does Aetrix verify that SMBJ78C is sourced from the original manufacturer or authorized distributors?
All SMBJ78C 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 SMBJ78C meets industry standards.
7.What is the process for return or replacement of SMBJ78C?
All SMBJ78C units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ78C, 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 SMBJ78C part is unused and in its original packaging.
Return procedure for SMBJ78C:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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