Taiwan Semiconductor Corporation BZW04-9V4

Overview

BZW04-9V4 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 9.4 V working stand-off voltage, 10.5–11.6 V breakdown voltage at 1 mA test current, 15.6 V maximum clamping voltage at 25.7 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 BZW04-9V4 datasheet, BZW04-9V4 pinout, BZW04-9V4 application, or BZW04-9V4 equivalent, key selection criteria include clamping voltage margin relative to protected IC V_DD, leakage current below 5 µA at 9.4 V, thermal resistance of 100 °C/W on PCB, and DO-41 package compatibility with manual or wave-soldered assembly.

Technical Context

The BZW04-9V4 operates as a silicon avalanche diode, triggering conduction when reverse voltage exceeds its specified breakdown range (10.5–11.6 V). Its low dynamic impedance ensures rapid voltage clamping during fast transients such as EFT (IEC 61000-4-4) and ISO 7637-2 pulse 1/2a.

It is rated for junction temperatures from –55 °C to +175 °C, supports 40 A non-repetitive forward surge current (8.3 ms half-sine), and exhibits a temperature coefficient of 0.075 %/°C for V_BR, enabling stable performance across automotive under-hood environments.

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 SMBJ9.0A and P6KE9.1A, the BZW04-9V4 offers identical clamping performance in a smaller DO-41 axial package, AEC-Q101 qualification path, and tighter V_BR tolerance - making it optimal for cost-sensitive, high-volume automotive modules requiring proven reliability and legacy through-hole compatibility.

Availability

BZW04-9V4 is available at Aetrix Electronics and suitable for automotive lighting control, industrial PLC I/O protection, and DC power supply input stage applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for BZW04-9V4 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-grade transient suppression, targeting ISO 7637-2 and IEC 61000-4-5 compliance in engine control, lighting, and body electronics - with emphasis on high-temperature stability and AEC-Q101 qualification readiness.

FAQ

What is the maximum clamping voltage of the BZW04-9V4 under standard surge conditions?

The BZW04-9V4 has a maximum clamping voltage (V_C) of 15.6 V when subjected to a 10/1000 µs waveform with a peak pulse current (I_PP) of 25.7 A. This value is measured per ANSI/IEEE C62.35 standards and represents the highest voltage seen across the device during surge conduction - critical for ensuring protected ICs remain within their absolute maximum voltage ratings. The BZW04-9V4 maintains this clamping performance across its full operating temperature range.

Is the BZW04-9V4 unidirectional or bidirectional, and how is polarity identified?

The BZW04-9V4 is a unidirectional TVS diode, intended for DC line protection where polarity is fixed. Polarity is marked by a cathode band on the DO-41 package body - the banded end connects to the protected line (e.g., 12 V rail), while the unbanded end connects to ground. Bidirectional variants (e.g., BZW04-9V4B) exist but are distinct orderable parts; the BZW04-9V4 itself is strictly unidirectional and must be oriented correctly in-circuit.

Does the BZW04-9V4 meet AEC-Q101 requirements for automotive use?

The base BZW04-9V4 is not AEC-Q101 qualified; however, the variant BZW04-9V4H (with "H" suffix) is explicitly qualified per AEC-Q101 Rev D for stress testing including HTGB, AC-H3TRB, and temperature cycling. For automotive applications requiring formal qualification, BZW04-9V4H must be specified - the BZW04-9V4 itself is suitable for non-qualified automotive or industrial use where full AEC validation is not mandated.

What is the thermal resistance of the BZW04-9V4, and how does it affect layout design?

The BZW04-9V4 has a junction-to-ambient thermal resistance (R_θJA) of 100 °C/W when mounted on a standard PCB with 10 mm lead lengths. This value assumes typical copper pad area and airflow; designers must ensure adequate copper pour around leads and avoid thermal isolation to prevent junction overheating during repetitive surges. Derating curves in the datasheet require power reduction above 25 °C ambient - for example, at 75 °C ambient, the BZW04-9V4's steady-state dissipation drops to ~0.5 W.

Can the BZW04-9V4 be used in place of a Zener diode for voltage regulation?

No - the BZW04-9V4 is not designed for voltage regulation. It is optimized for transient suppression: its V_BR has wide tolerance (10.5–11.6 V), leakage rises sharply above V_WM, and it lacks the stable dynamic impedance needed for precision regulation. While it conducts heavily during overvoltage, it does not regulate continuously like a Zener. For regulation, dedicated Zener diodes (e.g., MMSZ4684) with tighter V_Z tolerance and specified Z_ZT should be used instead of the BZW04-9V4.