Taiwan Semiconductor Corporation KBU405G

Overview

KBU405G from Taiwan Semiconductor is a 4A, 600V repetitive peak reverse voltage (V_RRM) glass-passivated standard bridge rectifier in KBU package, featuring 150A surge capability, 1.1V max forward voltage at 4A, and <5µA reverse current at 25°C - used in AC/DC front-end stages of offline SMPS and LED drivers.

For engineers reviewing the KBU405G datasheet, KBU405G pinout, KBU405G application, or KBU405G equivalent, key selection criteria include V_RRM = 600V, I_F = 4A, thermal resistance R_θJC = 4°C/W, and UL recognition E-326243 for safety-critical power conversion designs.

Technical Context

KBU405G integrates four silicon diodes in a single-phase full-wave bridge configuration with glass-passivated junctions for enhanced reliability under thermal cycling and humidity stress. Its KBU molded package provides UL 94V-0 flammability rating and matte tin-plated leads compliant with J-STD-002 solderability.

The device operates across -55°C to +150°C junction temperature range, supports 8.3ms half-sine surge up to 150A (I²t = 93 A²s), and delivers typical junction capacitance of 240pF per diode at 1MHz/4V - enabling stable performance in high-frequency switching environments.

Key Specifications

Pinout & Package

Package: KBU - molded plastic case with 4 axial leads (AC1, AC2, +, –), UL 94V-0 rated, 7.2g weight, 0.56 N·m max mounting torque.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bridge rectifier applications.

Compared with GBU4K and W04M, KBU405G offers optimal balance of 600V rating, 150A surge headroom, and KBU package thermal performance - making it preferred for universal-input SMPS where safety margin, reliability, and thermal efficiency are jointly prioritized.

Availability

KBU405G is available at Aetrix Electronics and suitable for switching mode power supplies, LED lighting drivers, and industrial AC/DC adapters requiring stable component supply and UL-recognized reliability.

Supply support for KBU405G 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, serving global power and signal conditioning markets since 1979.

KBU405G belongs to TSC's standard bridge rectifier product line, engineered for high-efficiency, high-reliability AC/DC conversion in cost-sensitive yet safety-critical industrial and consumer power systems.

FAQ

What is the maximum repetitive peak reverse voltage (V_RRM) for KBU405G?

KBU405G has a V_RRM of 600 V, meaning it can block up to 600 volts of reverse voltage repeatedly without breakdown. This value is specified in the Absolute Maximum Ratings table of the official Taiwan Semiconductor datasheet (Version J2103) and defines the upper limit for safe AC input voltage derating - e.g., supporting 230VAC mains with ≥2× safety margin. Exceeding this rating risks irreversible junction failure.

Does KBU405G require a heatsink in typical 4A operation?

KBU405G can operate without an external heatsink at ambient temperatures ≤40°C and case temperatures ≤75°C under natural convection, thanks to its R_θJC = 4°C/W and R_θJA = 19°C/W. However, sustained 4A load at higher ambient or with limited airflow necessitates a heatsink - especially when mounted on FR-4 PCBs without copper pour. Thermal design must verify actual case temperature using measured power dissipation (P_D ≈ I_F × V_F) and ambient conditions.

Is KBU405G RoHS compliant and lead-free?

Yes, KBU405G is RoHS compliant and lead-free per EU Directive 2011/65/EU, as confirmed in the "Features" section of the Taiwan Semiconductor datasheet (Version J2103). Its matte tin-plated leads meet J-STD-002 solderability requirements, and the molding compound satisfies UL 94V-0 flammability rating - ensuring compatibility with modern lead-free reflow processes and environmental compliance for global shipments.

What is the marking code printed on the KBU405G package?

The top surface of the KBU405G package is marked "KBU405G", followed by date code (YWW format) and factory code (e.g., "F"). This marking aligns with the Package Outline Dimensions diagram in the Taiwan Semiconductor datasheet (Page 4, Version J2103) and enables traceability and visual identification during assembly and inspection. No additional symbols or secondary codes are present on standard production units.

How does KBU405G compare to KBU406G in terms of voltage rating and interchangeability?

KBU405G has V_RRM = 600 V, while KBU406G is rated for 800 V - a 200 V difference that prevents direct substitution without circuit review. Both share identical I_F = 4 A, package (KBU), pinout, and thermal specs, but using KBU405G in a design originally specifying KBU406G risks reverse breakdown under high-line transients. Always verify worst-case reverse stress before interchanging KBU405G for KBU406G or vice versa.