Taiwan Semiconductor Corporation BZW04-7V8

Overview

BZW04-7V8 from Taiwan Semiconductor is a unidirectional transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power rails and signal lines. It features a 7.78 V working stand-off voltage, 8.65–9.55 V breakdown voltage at 1 mA, 13.4 V maximum clamping voltage at 30 A peak pulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - deployed in automotive lighting control modules to absorb load-dump transients.

For engineers reviewing the BZW04-7V8 datasheet, BZW04-7V8 pinout, BZW04-7V8 application, or BZW04-7V8 equivalent, key selection criteria include clamping voltage margin relative to protected IC V_DD, leakage current below 50 µA at V_WM, thermal resistance (R_θJL = 60 °C/W), DO-41 package compatibility with manual and automated assembly, and AEC-Q101 qualification status for automotive use.

Technical Context

The BZW04-7V8 operates as a silicon avalanche diode, triggered when reverse voltage exceeds its breakdown threshold (V_BR = 8.65–9.55 V), diverting surge current away from downstream circuitry. Its low dynamic impedance ensures rapid voltage clamping during fast transients such as EFT (IEC 61000-4-4) and ISO 7637-2 pulses.

It is rated for 175 °C maximum junction temperature and exhibits a positive temperature coefficient of V_BR (+0.068 %/°C), enabling stable performance across automotive ambient ranges. The device supports both single-pulse (non-repetitive) and steady-state dissipation (1 W at T_L = 75 °C) with defined derating above 25 °C.

Key Specifications

Pinout & Package

Package: DO-204AL (DO-41), axial leaded, epoxy-molded case with cathode band marking for unidirectional polarity. Leads are pure tin-plated, solderable per J-STD-002, and meet JESD 201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Compared with SMBJ7.0A and P6KE7.8A, the BZW04-7V8 offers optimal balance of DO-41 compatibility, 50 µA leakage, and AEC-Q101 availability - making it the preferred choice for new automotive electronics where footprint, reliability, and low-quiescent design are jointly constrained.

Availability

BZW04-7V8 is available at Aetrix Electronics and suitable for automotive lighting control, industrial PLC I/O protection, and smart meter power supply applications requiring stable component supply, long-term lifecycle support, and AEC-Q101-compliant sourcing.

Supply support for BZW04-7V8 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 management devices since 1979.

The BZW04 series was developed specifically for automotive and industrial transient suppression, emphasizing robust surge handling, low clamping voltage, and AEC-Q101 qualification - targeting 12 V/24 V DC systems subject to ISO 7637-2 and IEC 61000-4-x threats.

FAQ

What is the maximum clamping voltage of the BZW04-7V8 under standard test conditions?

The BZW04-7V8 has a maximum clamping voltage (V_C) of 13.4 V when subjected to a 30 A peak pulse current with a 10/1000 µs waveform at T_A = 25 °C. This value is measured per ANSI/IEEE C62.35 and defines the upper voltage limit imposed on protected circuitry during surge events. The BZW04-7V8 maintains this clamping performance consistently across its qualified operating temperature range, making it suitable for automotive environments where voltage margins are tightly constrained.

Is the BZW04-7V8 unidirectional or bidirectional, and how is polarity identified?

The BZW04-7V8 is a unidirectional TVS diode, indicated by the absence of "B" suffix (e.g., BZW04-7V8B 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 (cathode), while the unbanded end connects to ground (anode). This configuration enables forward conduction only during negative transients on the protected line, aligning with standard DC rail protection topology. The BZW04-7V8 must be installed with correct orientation to function as intended.

Does the BZW04-7V8 meet AEC-Q101 qualification requirements?

The base BZW04-7V8 part is not AEC-Q101 qualified; however, the AEC-Q101-qualified version is designated BZW04-7V8H (with "H" suffix). This variant undergoes full stress testing per AEC-Q101 Rev D, including HTGB, H3TRB, and temperature cycling, and is approved for automotive under-hood and cabin applications. For designs requiring automotive qualification, specify BZW04-7V8H - the BZW04-7V8 itself is intended for industrial and commercial use unless otherwise validated. Always verify qualification status via Taiwan Semiconductor's official product change notices.

What is the thermal resistance and power derating behavior of the BZW04-7V8?

The BZW04-7V8 has a junction-to-lead thermal resistance (R_θJL) of 60 °C/W and a junction-to-ambient resistance (R_θJA) of 100 °C/W on a PCB with 10 mm lead length. Its peak pulse power (400 W) is derated linearly above 25 °C ambient per Figure 2 in the datasheet, and steady-state power (1 W) is derated above 75 °C lead temperature. These values directly inform heatsinking requirements and layout decisions - for example, mounting on 5 × 5 mm copper pads per lead reduces R_θJA and improves surge survivability. The BZW04-7V8's thermal profile supports sustained operation in engine bay environments up to 125 °C ambient when properly implemented.

How does the BZW04-7V8 compare to the BZW04-7V0 and BZW04-8V5 in terms of clamping performance?

The BZW04-7V8 provides a clamping voltage of 13.4 V at 30 A, positioned between BZW04-7V0 (12.1 V at 33 A) and BZW04-8V5 (14.5 V at 27.6 A). Its V_WM of 7.78 V offers tighter margin above typical 5 V logic rails than BZW04-7V0 (7.02 V), while avoiding excessive margin loss versus BZW04-8V5 (8.55 V). The BZW04-7V8 thus balances protection level and system compatibility - especially valuable in 12 V automotive subsystems where V_DD tolerances are narrow. All three share identical DO-41 packaging and 400 W rating, enabling direct substitution based on clamping voltage target.