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Taiwan Semiconductor Corporation SMBJ78CA
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- Part No.:
- SMBJ78CA
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ78CA.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AA
- Quantity:
- Payment:
- Shipping:
Inventory:2,750
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Product details
Overview
SMBJ78CA from Taiwan Semiconductor is a bidirectional 600W surface-mount transient voltage suppressor (TVS) diode in DO-214AA (SMB) package, designed for high-energy ESD and surge protection in automotive and industrial power rails. It features a 78V working stand-off voltage (VWM), 86.7–106V breakdown voltage (VBR), 126V maximum clamping voltage (VC) at 5.0A peak impulse current, and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b standards.
For engineers reviewing the SMBJ78CA datasheet, SMBJ78CA pinout, SMBJ78CA application, or SMBJ78CA equivalent, key selection criteria include bidirectional clamping capability, low leakage (<1µA at 78V), fast response (<1.0ps), UL 94V-0 molding compound, and compatibility with automated SMT placement on 12V–48V DC systems requiring robust transients immunity.
Technical Context
The SMBJ78CA implements a silicon avalanche junction structure with glass passivation for stable breakdown behavior under repetitive surge stress. Its bidirectional configuration enables symmetrical clamping across both polarities without external polarity management, supporting protection of differential buses and AC-coupled signal lines.
Thermal performance is defined by RθJC = 10°C/W and RθJA = 55°C/W, enabling reliable operation up to TJ = +150°C. The device sustains non-repetitive 10/1000µs waveform surges up to 600W while maintaining VC ≤ 126V at IPP = 5.0A - critical for safeguarding downstream MOSFETs and microcontrollers in 24V/48V vehicle electronics.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before clamping begins; sets minimum system rail margin for 24V/48V applications. |
| VBR min / max | 86.7 V / 106 V - Breakdown occurs within this range at 1 mA test current; ensures predictable turn-on during transients. |
| VC @ IPP | 126 V at 5.0 A - Clamped voltage during 10/1000µs surge; limits stress on protected ICs to safe levels. |
| PPK | 600 W - Peak pulse power handling per single 10/1000µs event; supports ISO 7637-2 Pulse 5a compliance. |
| ID @ VWM | <1 µA - Ultra-low leakage at rated stand-off voltage; avoids parasitic loading on high-impedance sensor or reference circuits. |
| TJ max | +150 °C - Maximum junction temperature; allows operation in under-hood automotive environments. |
| Package | DO-214AA (SMB) - Standardized surface-mount outline with 0.090 g mass and JESD201 Class 2 whisker resistance. |
Pinout & Package
DO-214AA (SMB) package: molded plastic case with matte tin-plated leads, cathode band marking for unidirectional variants; SMBJ78CA is bidirectional and marked with "NT" code - no polarity band required. Leads are solderable per J-STD-002, moisture sensitivity level 1 (J-STD-020).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Bidirectional avalanche junction terminals | No functional polarity - either terminal serves as anode or cathode depending on transient polarity; eliminates orientation constraints during PCB layout. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC lines, differential buses (e.g., CAN FD, RS-485), and floating power domains without polarity awareness. |
| Fast response time | <1.0 ps - Limits voltage overshoot during nanosecond-scale ESD events (IEC 61000-4-2), preserving signal integrity in high-speed interfaces. |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive load dump), Pulse 2a/2b (battery disconnect), and Pulse 3a/3b (switching noise); suitable for automotive body control modules. |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU; supports green manufacturing and end-of-life recycling requirements. |
| Automated placement ready | DO-214AA footprint and lead geometry optimized for pick-and-place machines; reduces assembly cost in high-volume industrial controls. |
Applications
| Automotive Power Rail Protection | Industrial PLC I/O Protection |
|---|---|
Use Scenario: Protecting 24V supply inputs in engine control units (ECUs) against load dump and alternator transients per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Primary clamping device placed directly at connector entry point to shunt surge energy before it reaches DC-DC converters and MCU power rails. Use Value: Limits peak voltage to ≤126V during 600W transients, preventing latch-up or permanent damage to 3.3V/5V logic supplies downstream. |
Use Scenario: Safeguarding digital input channels on programmable logic controllers exposed to inductive switching noise from solenoids and contactors. IC Role / Device Role / Timing Role: Bidirectional TVS placed across each 24V digital input to clamp both positive and negative polarity transients induced by relay coil de-energization. Use Value: Maintains signal integrity by clamping spikes within 1.0ps, ensuring reliable state detection without false triggering or input latch-up. |
| LED Driver Overvoltage Protection | RS-485 Transceiver Bus Protection |
Use Scenario: Shielding constant-current LED drivers in street lighting systems from lightning-induced surges on long outdoor wiring runs. IC Role / Device Role / Timing Role: High-power TVS connected between output and ground to absorb 10/1000µs surges exceeding 600W without degradation. Use Value: Withstands ≥1000 surge events at rated PPK, extending driver lifetime in harsh outdoor environments where replacement is costly. |
Use Scenario: Protecting half-duplex RS-485 transceivers in building automation networks from ESD and cable discharge events. IC Role / Device Role / Timing Role: Bidirectional clamping device placed across A/B differential pair to suppress common-mode transients while preserving signal swing. Use Value: Junction capacitance <100 pF at 0 V ensures minimal signal distortion at data rates up to 10 Mbps, maintaining bus timing margins. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ78CA | Same DO-214AC (SMA) package; slightly higher VBR min (88.9 V) and VC (128 V); RθJA = 65°C/W vs. 55°C/W. | Lower thermal efficiency requires larger copper area for same power derating; less suitable for compact automotive modules. | Prefer SMBJ78CA when board space is constrained and thermal management is limited. |
| ON Semiconductor 1.5SMC78CA | DO-214AB (SMC) package (larger footprint); identical VWM/VBR/VC specs; higher PPK (1500W) but same 10/1000µs rating. | Requires PCB redesign due to 7.11 mm × 6.22 mm SMC vs. 4.57 mm × 3.94 mm SMB; over-spec'd for most 600W use cases. | Choose SMBJ78CA for cost-sensitive, space-constrained designs where 600W rating is sufficient. |
Compared with SMAJ78CA and 1.5SMC78CA, SMBJ78CA delivers optimal balance of compact DO-214AA packaging, superior thermal resistance (55°C/W), and precise 600W surge handling - making it ideal for automotive ECUs, industrial I/O modules, and LED drivers where size, thermal headroom, and application-matched rating are critical.
Availability
SMBJ78CA is available at Aetrix Electronics and suitable for automotive power rail protection, industrial PLC I/O protection, and LED driver overvoltage protection requiring stable component supply across production lifecycles.
Supply support for SMBJ78CA 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 SMBJ series was developed specifically for high-reliability transient suppression in automotive electronics and industrial control systems, emphasizing ISO 7637-2 compliance, low leakage, and automated assembly compatibility.
FAQ
What is the clamping voltage of SMBJ78CA at its rated peak pulse current?
The SMBJ78CA has a maximum clamping voltage (VC) of 126 V when subjected to a 10/1000 µs surge waveform at 5.0 A peak impulse current (IPP). This value is measured per ANSI/IEEE C62.35 and ensures downstream components see limited overvoltage stress during standardized transients - a key parameter verified in SMBJ78CA's electrical specifications table.
Is SMBJ78CA unidirectional or bidirectional, and how is polarity indicated?
SMBJ78CA is a bidirectional TVS diode - it clamps transients of either polarity symmetrically and does not require orientation during PCB placement. Unlike unidirectional variants (e.g., SMBJ78A), SMBJ78CA carries no cathode band marking; its marking code is "NT", consistent with TSC's bidirectional SMBJ family designation per ordering information.
Does SMBJ78CA meet automotive transient immunity standards?
Yes, SMBJ78CA is explicitly rated to meet ISO 7637-2 Pulse 1 (inductive load dump), Pulse 2a/2b (battery disconnection), and Pulse 3a/3b (switching noise) requirements. This compliance is stated in the FEATURES section and validated through standardized 10/1000 µs surge testing - confirming SMBJ78CA's suitability for automotive body electronics and powertrain modules.
What is the maximum junction temperature and thermal resistance of SMBJ78CA?
SMBJ78CA has a maximum junction temperature (TJ) of +150°C and thermal resistances of RθJC = 10°C/W (junction-to-case) and RθJA = 55°C/W (junction-to-ambient). These values are specified in the THERMAL PERFORMANCE section and enable accurate thermal design for SMBJ78CA in sealed enclosures or high-ambient environments like under-hood automotive locations.
How does SMBJ78CA differ from SMBJ78A in terms of electrical performance?
SMBJ78CA is bidirectional with symmetrical VBR (86.7–106 V) and clamping in both directions, while SMBJ78A is unidirectional with forward voltage (VF) = 5.0 V at 50 A. SMBJ78CA has lower leakage (<1 µA at 78 V) and no forward conduction path - making it appropriate for AC-coupled or floating systems where polarity reversal must be handled without rectification.
SMBJ78CA 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:
- 126V
- Current - Peak Pulse (10/1000µs):
- 4.8A
- 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)
SMBJ78CA FAQ
1.How can I place an order for SMBJ78CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ78CA 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 SMBJ78CA reliable?
The price and inventory of SMBJ78CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ78CA is usually 5 days.
3.What payment methods are accepted for SMBJ78CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ78CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ78CA?
SMBJ78CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ78CA 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 SMBJ78CA?
For technical support, including SMBJ78CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ78CA requirements.
6.How does Aetrix verify that SMBJ78CA is sourced from the original manufacturer or authorized distributors?
All SMBJ78CA 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 SMBJ78CA meets industry standards.
7.What is the process for return or replacement of SMBJ78CA?
All SMBJ78CA units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ78CA, 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 SMBJ78CA part is unused and in its original packaging.
Return procedure for SMBJ78CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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