Taiwan Semiconductor Corporation KBU604G

Overview

KBU604G from Taiwan Semiconductor is a 6A, 400V repetitive peak reverse voltage (VRRM) glass-passivated single-phase bridge rectifier in KBU package, featuring 175A surge current capability, 1.1V max forward voltage at 6A, and <5µA reverse leakage at 25°C - used in AC/DC front-end stages of compact switching power supplies.

For engineers reviewing the KBU604G datasheet, KBU604G pinout, KBU604G application, or KBU604G equivalent, key selection criteria include VRRM margin for line-voltage transients, thermal resistance (RθJA = 8.6°C/W), IFSM derating under surge conditions, and RoHS-compliant matte tin-plated leads for reliable PCB soldering.

Technical Context

The KBU604G integrates four silicon diodes in a single-phase full-wave bridge configuration with glass-passivated junctions for enhanced reliability and moisture resistance. Its quad-diode layout enables direct AC input rectification without external interconnects, supporting high-density SMPS layouts where space and thermal management are constrained.

Designed for operation up to TJ = 150°C, it delivers stable performance under continuous 6A DC output load with RθJC = 3.1°C/W enabling efficient heatsink coupling. The device meets UL 94V-0 flammability and JESD201 Class 1A whisker requirements, confirming suitability for industrial-grade power conversion.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with GBU6K and DF08MA, the KBU604G offers the lowest RθJA (8.6°C/W) and tightest IR spec (≤5µA), making it optimal for thermally dense, low-standby-power designs requiring long-term reliability under thermal cycling.

Availability

KBU604G is available at Aetrix Electronics and suitable for switching mode power supplies, LED lighting drivers, and USB-C wall adapters requiring stable component supply across production volumes and lifecycle phases.

Supply support for KBU604G 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 power rectifiers, TVS diodes, and MOSFETs since 1979.

The KBU series was developed specifically for high-reliability, high-surge AC/DC front-end rectification in compact, thermally constrained power supplies targeting global safety and environmental standards.

FAQ

What is the maximum repetitive peak reverse voltage (VRRM) rating for KBU604G?

The KBU604G has a VRRM rating of 400 V, verified per Taiwan Semiconductor's official datasheet revision J2103. This value is fixed for the KBU604G variant and distinguishes it from other members of the KBU601G–KBU607G family. Designers must ensure this rating exceeds the peak AC input voltage plus safety margin in their application. The KBU604G is not rated for 600 V or higher reverse stress.

Does KBU604G support surface-mount assembly?

No, the KBU604G uses a through-hole KBU package with four axial leads and is not compatible with SMT reflow processes. It requires wave soldering or hand soldering. The lead finish is matte tin per J-STD-002, and mounting torque must not exceed 0.56 N·m. For SMT alternatives, consider the GBU6K in SOIC-4 or discrete SOD-123 diode bridges - but those differ electrically and mechanically from the KBU604G.

What is the typical forward voltage drop of KBU604G at full rated current?

At 6 A and TJ = 25°C, the KBU604G exhibits a maximum forward voltage (VF) of 1.1 V per diode pair in conduction - meaning total bridge drop is ~2.2 V under worst-case conditions. Typical VF is lower, but design margins must use the 1.1 V max value. This directly impacts conduction loss (P = IF × VF) and thermal design in continuous-duty applications.

Is KBU604G RoHS compliant and halogen-free?

Yes, the KBU604G is RoHS compliant as stated in the official documentation (Version J2103). While the datasheet confirms RoHS compliance, it does not explicitly declare halogen-free status. The molding compound meets UL 94V-0, but halogen content is not specified. For halogen-free requirements, consult Taiwan Semiconductor's material declaration sheet or contact their technical support directly for KBU604G-specific substance data.

Can KBU604G replace KBU606G in a 600V design?

No, KBU604G cannot safely replace KBU606G in a 600V design. KBU606G has a VRRM of 800 V, whereas KBU604G is rated only for 400 V. Using KBU604G in a circuit exposed to >400V reverse stress risks catastrophic avalanche failure. Substitution requires verifying all voltage transients, including line surges and ringing, remain below 400V - which is generally not feasible in 600V-rated systems. Always match VRRM to system-level stress requirements.