Taiwan Semiconductor Corporation BZW04-40

Overview

BZW04-40 from Taiwan Semiconductor is a unidirectional transient voltage suppressor (TVS) diode designed for high-energy surge protection in DC power rails and signal lines. It features a 40.2 V working stand-off voltage, 44.7–49.4 V breakdown voltage at 1 mA test current, 6.2 A peak impulse current, 64.8 V clamping voltage at rated surge, and 400 W peak pulse power rating per 10/1000 μs waveform - deployed in automotive lighting control and industrial sensor interface circuits.

For engineers reviewing the BZW04-40 datasheet, BZW04-40 pinout, BZW04-40 application, or BZW04-40 equivalent, key selection criteria include clamping voltage margin relative to protected IC V_DD, junction temperature derating above 25°C, lead-to-lead thermal resistance (60°C/W), and AEC-Q101 qualification status for automotive-grade reliability validation.

Technical Context

The BZW04-40 operates as a silicon avalanche diode with unidirectional polarity, triggered when reverse voltage exceeds its specified breakdown range. Its low dynamic impedance ensures rapid clamping response (<1 ns typical), while the DO-204AL (DO-41) package supports through-hole mounting with pure tin-plated leads compliant to J-STD-002 solderability standards.

Thermal performance is defined by R_θJL = 60°C/W (junction-to-lead) and R_θJA = 100°C/W (junction-to-ambient on PCB with 10 mm leads), enabling operation across -55°C to +175°C junction temperature range. The device exhibits <1 μA reverse leakage at 40.2 V and a 0.101%/°C temperature coefficient of V_BR.

Key Specifications

Pinout & Package

Package: DO-204AL (DO-41), axial-leaded, epoxy-molded case meeting UL 94V-0 flammability rating; cathode indicated by band marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ40A and P4KE40A, the BZW04-40 offers identical electrical clamping performance in a smaller DO-41 axial package with verified AEC-Q101 availability, making it optimal for legacy through-hole designs needing automotive compliance without SMT conversion.

Availability

BZW04-40 is available at Aetrix Electronics and suitable for automotive lighting control, industrial sensor interface, and 40 V power supply input protection requiring stable component supply and long-term lifecycle support.

Supply support for BZW04-40 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, with global distribution and AEC-Q101 qualification capabilities.

The BZW04 series is part of TSC's high-reliability transient suppression portfolio, engineered specifically for automotive and industrial applications demanding robust 400 W surge immunity in compact axial packages.

FAQ

What is the maximum clamping voltage of the BZW04-40 under surge conditions?

The BZW04-40 has a maximum clamping voltage (V_C) of 64.8 V when subjected to its rated peak impulse current of 6.2 A under the standard 10/1000 μs waveform. This value is measured per ANSI/IEEE C62.35 and defines the upper voltage limit imposed on protected circuitry during transient events - critical for ensuring compatibility with 65 V-tolerant ICs in 40 V systems. The BZW04-40 maintains this clamping performance across its full operating temperature range.

Is the BZW04-40 available in an AEC-Q101 qualified version?

Yes, the BZW04-40H variant is explicitly qualified to AEC-Q101 for automotive applications. This qualification includes stress testing for temperature cycling, humidity bias, mechanical shock, and accelerated life testing - confirming suitability for under-hood and body electronics. The base BZW04-40 (non-H suffix) is not AEC-Q101 certified; designers must specify the 'H' suffix to receive the qualified version. The BZW04-40H retains identical electrical parameters and DO-204AL packaging.

What is the reverse leakage current specification for the BZW04-40 at its working stand-off voltage?

The BZW04-40 exhibits a maximum reverse leakage current (I_D) of 1 μA when biased at its working stand-off voltage (V_WM) of 40.2 V, measured at 25°C ambient. This ultra-low leakage minimizes quiescent power draw in battery-powered or energy-sensitive systems. Leakage remains below 5 μA up to 125°C junction temperature, supporting reliable operation in thermally demanding environments without compromising standby efficiency. The BZW04-40 achieves this while maintaining full 400 W surge capability.

How does the thermal resistance of the BZW04-40 affect PCB layout decisions?

The BZW04-40 has a junction-to-lead thermal resistance (R_θJL) of 60°C/W and junction-to-ambient resistance (R_θJA) of 100°C/W on a PCB with 10 mm lead lengths. To maintain T_J ≤175°C at full 400 W surge, designers must ensure adequate copper pour area around both leads and avoid excessive trace length or narrow traces that increase thermal impedance. The BZW04-40's DO-204AL package relies on lead conduction rather than case dissipation, so thermal vias under pads provide minimal benefit unless leads are soldered to large internal planes.

Can the BZW04-40 be used in bidirectional configurations?

No - the BZW04-40 is a unidirectional TVS diode and must be used with correct polarity (cathode toward the protected line). For bidirectional protection, the designated variant is BZW04-40B, which features symmetrical breakdown in both directions and identical V_BR, V_C, and P_PK ratings. Using the unidirectional BZW04-40 in AC or floating signal paths risks forward conduction and failure. Always match the device suffix ('B' for bidirectional) to the circuit topology - the BZW04-40 is strictly for DC rail clamping.