Taiwan Semiconductor Corporation BZW04-85

Overview

BZW04-85 from Taiwan Semiconductor is a unidirectional transient voltage suppressor diode designed for high-energy surge protection in DC power rails and signal lines. It features a 85.5 V working stand-off voltage, 95–105 V breakdown voltage at 1 mA test current, 137 V maximum clamping voltage at 2.9 A peak impulse current, 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 BZW04-85 datasheet, BZW04-85 pinout, BZW04-85 application, or BZW04-85 equivalent, key selection criteria include clamping voltage margin vs. protected IC V_DD, leakage current at operating bias, thermal derating above 25°C ambient, and DO-41 lead-form compatibility with manual or wave-solder assembly.

Technical Context

The BZW04-85 operates as a silicon avalanche diode with sharp reverse-breakdown knee and low dynamic impedance during transient events. Its 137 V clamping voltage at 2.9 A ensures robust overvoltage limiting for 75–100 V nominal systems, while its <1 µA reverse leakage at 85.5 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 PCB pads. The device sustains 400 W non-repetitive surges per IEC 61000-4-5 (10/1000 µs) and meets AEC-Q101 stress requirements when ordered with "H" suffix.

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 JEDEC JESD201 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 BZW04-85, SMBJ85A offers higher surge headroom in a surface-mount package requiring PCB redesign, while P6KE85A retains axial leads but sacrifices thermal performance and long-term reliability under repetitive stress - BZW04-85 balances DO-41 manufacturability, 400 W capability, and 175 °C junction rating for demanding automotive and industrial deployments.

Availability

BZW04-85 is available at Aetrix Electronics and suitable for automotive lighting control, industrial PLC analog input protection, and 48 V DC power rail surge suppression requiring stable component supply across multi-year production cycles.

Supply support for BZW04-85 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 headquartered in Hsinchu, Taiwan, specializing in discrete power devices, TVS diodes, rectifiers, and thyristors since 1979.

The BZW04 series was engineered for high-reliability transient suppression in automotive and industrial environments, emphasizing tight V_BR tolerance, low clamping ratio, and AEC-Q101 qualification readiness across voltage grades.

FAQ

What is the maximum clamping voltage of the BZW04-85 under rated surge conditions?

The BZW04-85 exhibits a maximum clamping voltage (V_C) of 137 V when subjected to its rated peak impulse current of 2.9 A using the 10/1000 µs waveform. This value is measured per ANSI/IEEE C62.35 and represents the upper voltage limit imposed on protected circuitry during a full-rated transient event. The BZW04-85 maintains this clamping performance consistently across its specified operating temperature range of –55 °C to +175 °C.

Is the BZW04-85 suitable for bidirectional transient protection?

No - the standard BZW04-85 is unidirectional. For bidirectional protection, the designated variant is BZW04-85B, which features symmetrical breakdown characteristics and no polarity marking. Both share identical V_WM, V_BR, and V_C values, but BZW04-85B must be used where AC-coupled or dual-polarity transients (e.g., RS-485 data lines) require suppression in both directions. The BZW04-85 itself is intended for DC rail protection with defined anode/cathode orientation.

What packaging options are available for the BZW04-85?

The BZW04-85 is offered in DO-204AL (DO-41) axial package with two standard packing formats: 5,000 units per tape-and-reel (standard ordering code BZW04-85) and 3,000 units per ammo box (ordering code BZW04-85A0G). AEC-Q101 qualified versions carry the "H" suffix (e.g., BZW04-85H) and are available in both pack types. All variants use pure tin-plated leads compliant with J-STD-002 solderability standards.

How does the BZW04-85 perform at elevated ambient temperatures?

The BZW04-85 follows standard derating curves: its 400 W peak pulse power is fully rated at T_A = 25 °C and linearly decreases to ~240 W at 75 °C ambient, per Figure 2 in the datasheet. Steady-state power dissipation remains limited to 1 W at T_L = 75 °C (lead temperature), with thermal resistance of 60 °C/W junction-to-lead. Engineers must verify board layout and copper area to maintain safe T_J ≤ 175 °C during sustained surge duty cycles. The BZW04-85 remains functional up to T_A = 125 °C with appropriate derating.

Does the BZW04-85 meet automotive qualification standards?

The base BZW04-85 is not AEC-Q101 qualified; however, the BZW04-85H variant is explicitly tested and certified to AEC-Q101 Rev D for stress tests including HTSL, TC, UHAST, and mechanical shock. Qualification applies to the DO-41 package configuration and covers the full temperature range (–55 °C to +175 °C). Designers targeting automotive applications must specify the "H" suffix part number to ensure compliance - the BZW04-85 alone does not carry this qualification.