Taiwan Semiconductor Corporation BZW04-7V8B

Overview

BZW04-7V8B from Taiwan Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in DO-204AL (DO-41) package, rated for 400W peak pulse power at 10/1000μs, with 7.78V working stand-off voltage, 8.65–9.55V breakdown voltage at 1mA, and 13.4V maximum clamping voltage at 30A peak impulse current. It protects automotive and industrial power rails against ESD and inductive switching transients.

For engineers reviewing the BZW04-7V8B datasheet, BZW04-7V8B pinout, BZW04-7V8B application, or BZW04-7V8B equivalent, key selection criteria include clamping voltage margin relative to protected IC V_DD, leakage current below 50μA at 7.78V, AEC-Q101 qualification status, thermal resistance (R_θJL = 60°C/W), and DO-41 lead-form compatibility with legacy PCB footprints.

Technical Context

The BZW04-7V8B operates as a silicon avalanche diode, triggered when reverse voltage exceeds its 8.65–9.55V breakdown threshold, diverting surge current away from downstream circuitry. Its low dynamic impedance ensures stable clamping at 13.4V under 30A 10/1000μs pulses, while junction temperature remains within -55°C to +175°C operating range.

Designed for unidirectional protection only, it features cathode band polarity marking, pure tin-plated leads compliant with J-STD-002, and meets UL 94V-0 flammability rating. The device exhibits <1μA reverse leakage above 10V and a 0.068%/°C temperature coefficient of V_BR, enabling predictable performance across automotive thermal environments.

Key Specifications

Pinout & Package

Package: DO-204AL (DO-41), axial-leaded, epoxy-molded case with cathode band marking for unidirectional polarity. Lead finish: pure tin, solderable per J-STD-002. Weight: 0.300 g.

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 BZW04-7V8B delivers optimal balance of 400W surge capacity, 13.4V clamping, DO-41 compatibility, and AEC-Q101 qualification-making it the preferred choice for cost-sensitive, thermally constrained automotive and industrial designs requiring validated reliability.

Availability

BZW04-7V8B is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, LED driver output stages, and AC/DC adapter input protection requiring stable component supply and long-term lifecycle support.

Supply support for BZW04-7V8B 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 Company (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for automotive, industrial, and consumer markets.

The BZW04 series was developed specifically for AEC-Q101-compliant transient suppression in harsh-environment automotive power systems, emphasizing robust clamping, low leakage, and thermal resilience in legacy through-hole packages.

FAQ

What is the polarity configuration of the BZW04-7V8B?

The BZW04-7V8B is a unidirectional TVS diode with cathode band marking indicating the cathode terminal. During normal operation, it blocks reverse voltage up to 7.78V; when voltage exceeds 8.65–9.55V, it avalanches and conducts from cathode to anode, shunting surge current to ground. This configuration is intended for DC line protection where polarity is fixed, unlike bidirectional variants used in AC or differential signal paths. The BZW04-7V8B does not conduct in forward bias beyond typical diode drop.

Is the BZW04-7V8B AEC-Q101 qualified?

Yes, the BZW04-7V8B is AEC-Q101 qualified, as confirmed by Taiwan Semiconductor's ordering code suffix "H" (BZW04-7V8BH would be the explicit AEC-Q101 version). While the base part number BZW04-7V8B shares identical electrical and mechanical specifications, qualification status depends on manufacturing lot traceability and test reporting. For automotive production, specify BZW04-7V8BH to ensure full AEC-Q101 documentation and lot-level compliance certification. The BZW04-7V8B itself is built on the same qualified process.

What is the maximum clamping voltage of the BZW04-7V8B under surge conditions?

The maximum clamping voltage of the BZW04-7V8B is 13.4V at 30A peak impulse current with a 10/1000μs waveform, as specified in Taiwan Semiconductor's official datasheet. This value represents the upper limit of voltage seen by protected circuitry during worst-case transient events. It is measured at T_A = 25°C and remains stable across the -55°C to +175°C operating junction temperature range due to the device's 0.068%/°C V_BR temperature coefficient. Designers must verify that 13.4V stays below the absolute maximum rating of downstream components.

Can the BZW04-7V8B replace the BZW04-7V0B in an existing design?

Yes, the BZW04-7V8B can replace the BZW04-7V0B if the design accommodates a higher V_WM (7.78V vs. 7.02V) and slightly higher V_BR (8.65–9.55V vs. 7.79–8.61V). Both share identical DO-41 packaging, thermal characteristics, and 400W rating. However, the increased standoff voltage reduces false triggering on noisy 7V rails, while the higher clamping voltage (13.4V vs. 12.1V) may require verification against protected IC tolerances. No PCB changes are needed, but system-level surge testing is recommended after substitution. The BZW04-7V8B offers improved noise immunity at the cost of marginally reduced clamping headroom.

What is the thermal resistance specification for the BZW04-7V8B?

The BZW04-7V8B has a junction-to-lead thermal resistance (R_θJL) of 60°C/W and a junction-to-ambient thermal resistance (R_θJA) of 100°C/W when mounted on a printed circuit board with 10mm lead length. These values are critical for calculating steady-state temperature rise under continuous power dissipation and for estimating transient thermal behavior during surge events. The low R_θJL enables efficient heat transfer from the silicon die to the PCB copper via the leads, supporting reliable operation at up to 1W steady-state power (P_D) at T_L = 75°C. The BZW04-7V8B's thermal performance is optimized for through-hole mounting with adequate copper pour.