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Taiwan Semiconductor Corporation BZW04-78
- Part No.:
- BZW04-78
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AL, DO-41, Axial
- Datasheet:
-
BZW04-78.pdf
- Description:
- TVS DIODE 78VWM 125VC DO204AL
- Quantity:
- Payment:
- Shipping:
Inventory:6,504
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Product details
Overview
BZW04-78 from Taiwan Semiconductor is a unidirectional transient voltage suppressor (TVS) diode designed for high-energy surge clamping in automotive and industrial power rails. It features a 78.0 V working stand-off voltage, 86.5–95.5 V breakdown voltage at 1 mA test current, 125 V maximum clamping voltage at 3.2 A peak pulse current, and 400 W peak pulse power rating per 10/1000 μs waveform - deployed to protect DC-DC converters and microcontroller I/O against load dump and EFT events.
For engineers reviewing the BZW04-78 datasheet, BZW04-78 pinout, BZW04-78 application, or BZW04-78 equivalent, key selection criteria include clamping voltage margin vs. protected IC's absolute maximum rating, junction temperature derating above 25°C ambient, unidirectional polarity marking, and DO-41 lead-form compatibility with through-hole PCB layouts.
Technical Context
The BZW04-78 operates as a silicon avalanche diode with sharp reverse-breakdown knee and low dynamic impedance during transient conduction. Its 125 V clamping voltage at 3.2 A ensures robust overvoltage limiting for 72 V nominal systems, while its <1 μA reverse leakage at 78 V supports low-power standby integrity.
Thermal design relies on junction-to-lead resistance of 60 °C/W and junction-to-ambient resistance of 100 °C/W on standard 10 mm leads; it sustains 175 °C maximum junction temperature and meets AEC-Q101 stress requirements when ordered with "H" suffix.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78.0 V - Maximum continuous reverse operating voltage before significant leakage begins |
| VBR min/max | 86.5 V / 95.5 V at 1 mA - Confirmed avalanche onset range for reliable turn-on threshold |
| VC @ IPP | 125 V at 3.2 A - Clamped voltage during 10/1000 μs surge, defining protection window for downstream ICs |
| PPK | 400 W - Peak pulse power handling capability under standardized surge waveform |
| TJ max | 175 °C - Maximum allowable junction temperature for sustained reliability in under-hood environments |
| RθJL | 60 °C/W - Junction-to-lead thermal resistance enabling direct heatsinking via PCB copper pads |
| ID @ VWM | <1 μA - Reverse leakage current ensuring minimal standby power loss in battery-backed circuits |
Pinout & Package
Package: DO-204AL (DO-41), axial-leaded, glass-passivated silicon junction, cathode band marked on case for unidirectional polarity identification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to system ground or lower-potential rail during clamping; defines unidirectional current path |
| Cathode | Reverse-biased terminal | Connected to protected line (e.g., 72 V supply); avalanche conduction initiates here during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified option | Available as BZW04-78H - validated for automotive-grade temperature cycling, humidity, and mechanical shock |
| Low clamping ratio | VC/VBR ≈ 1.33 - tight voltage margin between breakdown and clamping enables precise protection of 100 V-rated components |
| Fast response time | <1 ps - sub-nanosecond avalanche turn-on prevents transient energy from reaching sensitive circuitry |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU Directive 2011/65/EU - suitable for green manufacturing and export compliance |
| DO-41 mechanical robustness | UL 94V-0 molding compound + JESD201 Class 2 whisker resistance - ensures long-term solder joint integrity in vibration-prone environments |
Applications
| Automotive Load Dump Protection | Industrial DC Power Rail Clamping |
|---|---|
Use Scenario: 12 V/24 V vehicle electrical systems subjected to ISO 7637-2 Pulse 5a (load dump up to 120 V). IC Role / Device Role / Timing Role: Unidirectional TVS placed between alternator output and main fuse box to clamp transients before they reach ECUs and body control modules. Use Value: 125 V clamping voltage provides ≥15 V margin below typical 140 V load dump peak, preventing MOSFET gate oxide rupture in power distribution ICs. | Use Scenario: 48 V telecom rectifier outputs exposed to lightning-induced surges on outdoor cabinet feed lines. IC Role / Device Role / Timing Role: Primary surge suppression stage ahead of buck converter input, absorbing 400 W pulses without degradation. Use Value: 400 W peak power rating and 175 °C TJ max allow operation in sealed enclosures with limited airflow and elevated ambient temperatures. |
| ESD-Sensitive Sensor Interface Protection | Inductive Switching Transient Suppression |
Use Scenario: CAN transceiver inputs in automotive ADAS cameras subjected to IEC 61000-4-2 ±8 kV contact discharge. IC Role / Device Role / Timing Role: Secondary-level TVS mounted directly at connector entry point, shunting ESD current away from transceiver ESD diodes. Use Value: Sub-1 μA leakage at 78 V ensures no signal offset or bias shift in precision analog sensor front-ends sharing same supply rail. | Use Scenario: Relay coil driver circuits in factory automation PLC outputs generating >100 V flyback spikes during de-energization. IC Role / Device Role / Timing Role: Flyback snubber across relay coil, conducting stored inductive energy into safe dissipation path. Use Value: 3.2 A peak impulse current rating accommodates repetitive switching at 10 Hz without thermal runaway or parameter drift. |
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 | DO-214AA package (SMB), 78 V VWM, 125 V VC @ 3.2 A, same 400 W PPK but higher RθJA (110 °C/W) | Surface-mount only; requires reflow-compatible layout; less suited for high-vibration through-hole mounting | Select SMBJ78A only when board space constraints mandate SMD and thermal management uses thermal pads |
| P6KE78A | DO-15 package, 78 V VWM, 125 V VC @ 3.2 A, 600 W PPK but slower response and higher leakage (>5 μA) | Higher surge capacity but larger footprint and inferior ESD immunity due to parasitic capacitance | Choose P6KE78A only for cost-sensitive non-automotive applications where 600 W headroom justifies higher leakage and lower reliability |
Compared with SMBJ78A and P6KE78A, the BZW04-78 offers optimal balance of axial-leaded mechanical ruggedness, AEC-Q101 qualification path, and low-leakage performance - making it preferred for automotive under-hood and industrial field-deployed equipment requiring long-term stability.
Availability
BZW04-78 is available at Aetrix Electronics and suitable for automotive load dump protection, industrial DC power rail clamping, ESD-sensitive sensor interface protection, and inductive switching transient suppression requiring stable component supply across production lifecycles.
Supply support for BZW04-78 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 thyristors - headquartered in Hsinchu Science Park, Taiwan.
The BZW04 series belongs to TSC's AEC-Q101-qualified transient suppression portfolio, engineered specifically for automotive powertrain and chassis systems requiring high-reliability, high-energy surge immunity in harsh thermal and mechanical environments.
FAQ
What is the maximum clamping voltage of the BZW04-78 under a 10/1000 μs surge?
The BZW04-78 has a maximum clamping voltage (VC) of 125 V at 3.2 A peak pulse current under the standardized 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 verifying margin against downstream IC absolute maximum ratings.
Is the BZW04-78 unidirectional or bidirectional, and how is polarity identified?
The BZW04-78 is a unidirectional TVS diode, indicated by the absence of "B" suffix (BZW04-78B is the bidirectional variant). Polarity is marked by a cathode band on the DO-41 package body; the banded end connects to the protected line, while the anode connects to ground or lower potential.
Does the BZW04-78 meet automotive qualification standards?
Yes - the BZW04-78H variant is AEC-Q101 qualified, covering stress tests including temperature cycling, high-temperature operating life, and mechanical shock. Standard BZW04-78 (non-H) shares identical electrical specs but lacks formal automotive validation documentation and test reports.
What is the reverse leakage current of the BZW04-78 at its working stand-off voltage?
The BZW04-78 exhibits ≤1 μA reverse leakage current (ID) at its 78.0 V working stand-off voltage (VWM), measured at TA = 25°C. This ultra-low leakage preserves battery life in always-on automotive modules and avoids loading errors in high-impedance sensor bias networks.
Can the BZW04-78 be used in surface-mount designs?
No - the BZW04-78 is exclusively packaged in DO-204AL (DO-41), a through-hole axial-leaded format. For surface-mount equivalents, consider SMBJ78A (DO-214AA) or SMCJ78A (DO-214AB), which offer similar electrical specs but require PCB redesign and reflow process validation.
BZW04-78 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-204AL, DO-41, Axial
- Series:
- BZW04
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.5V
- Voltage - Clamping (Max) @ Ipp:
- 125V
- Current - Peak Pulse (10/1000µs):
- 3.2A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-204AL (DO-41)
BZW04-78 FAQ
1.How can I place an order for BZW04-78 through Aetrix?
Please submit a Request for Quotation (RFQ) for BZW04-78 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 BZW04-78 reliable?
The price and inventory of BZW04-78 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZW04-78 is usually 5 days.
3.What payment methods are accepted for BZW04-78?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZW04-78 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZW04-78?
BZW04-78 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZW04-78 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 BZW04-78?
For technical support, including BZW04-78 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZW04-78 requirements.
6.How does Aetrix verify that BZW04-78 is sourced from the original manufacturer or authorized distributors?
All BZW04-78 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 BZW04-78 meets industry standards.
7.What is the process for return or replacement of BZW04-78?
All BZW04-78 units undergo pre-shipment inspection (PSI). If there is an issue with BZW04-78, 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 BZW04-78 part is unused and in its original packaging.
Return procedure for BZW04-78:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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