Taiwan Semiconductor Corporation KBU402G

Overview

KBU402G from Taiwan Semiconductor is a 4A, 100V repetitive peak reverse voltage (V_RRM) glass-passivated standard bridge rectifier in KBU package, featuring 150A surge current capability, 1.1V max forward voltage at 4A, and <5µA reverse leakage at 25°C - deployed in AC/DC front-end stages of compact switch-mode power supplies.

For engineers reviewing the KBU402G datasheet, KBU402G pinout, KBU402G application, or KBU402G equivalent, key selection criteria include V_RRM margin for line-voltage transients, thermal resistance (R_θJA = 19°C/W), I_FSM rating for inrush handling, and UL recognition (E-326243) for safety-compliant designs.

Technical Context

The KBU402G integrates four silicon diodes in a single-phase full-wave bridge configuration with glass-passivated junctions for enhanced moisture and contamination resistance. Its KBU molded package supports PCB mounting with matte tin-plated leads compliant to J-STD-002 solderability and JESD201 Class 1A whisker resistance.

Thermally, it delivers R_θJC = 4°C/W to heatsink and R_θJA = 19°C/W in free-air, enabling sustained 4A average forward current (I_F) up to 150°C junction temperature. Reverse recovery is not specified; device operates as a standard (non-fast-recovery) rectifier.

Key Specifications

Pinout & Package

Package: KBU - molded plastic case with 4 axial leads (1–4), UL 94V-0 rated, 7.2 g mass, 0.56 N·m max mounting torque. Polarity marked on case.

Key Features

Applications

Equivalent & Alternatives

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

Compared with GBU4A and W04, the KBU402G offers optimal balance of 100 V V_RRM (suitable for 100–120 VAC regions), low V_F, and UL recognition - making it preferred for North American adapter and lighting applications where safety certification and thermal efficiency are prioritized over universal input range.

Availability

KBU402G is available at Aetrix Electronics and suitable for switching mode power supplies, wall adapters, and LED lighting applications requiring stable component supply, consistent parametric performance, and UL-recognized safety compliance.

Supply support for KBU402G 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 industrial, computing, and consumer markets since 1979.

The KBU402G belongs to TSC's standard bridge rectifier product line, engineered for cost-sensitive, high-volume AC/DC conversion in safety-certified power supplies where reliability, thermal robustness, and regulatory compliance are mandatory.

FAQ

What is the maximum repetitive peak reverse voltage (V_RRM) rating for the KBU402G?

The KBU402G has a V_RRM rating of 100 V, confirmed in the Absolute Maximum Ratings table of the official Taiwan Semiconductor datasheet (Version J2103). This value defines the highest instantaneous reverse voltage the device can block repeatedly without breakdown. It is distinct from the KBU401G (50 V) and KBU403G (200 V) in the same family. The KBU402G must not be used in circuits where peak reverse voltage exceeds 100 V.

Does the KBU402G have UL recognition, and what is the file number?

Yes, the KBU402G is UL Recognized under file number E-326243, as stated in the FEATURES section of the Taiwan Semiconductor datasheet. This applies to the entire KBU401G–KBU407G series. UL recognition confirms the device meets construction and flammability requirements per UL 62368-1 and UL 94V-0, enabling its use in end-product safety certifications without additional component-level testing.

What is the forward voltage drop (V_F) of the KBU402G at rated current?

The KBU402G exhibits a maximum forward voltage drop of 1.1 V at 4 A and 25°C junction temperature, per the Electrical Specifications table. At 2 A, V_F is ≤1.0 V under the same conditions. These values are measured per diode within the bridge; total conduction loss across the bridge equals 2 × V_F × I_F due to two-series diode conduction per half-cycle.

Is the KBU402G suitable for surface-mount assembly, or does it require through-hole mounting?

The KBU402G uses a KBU package with four axial leads intended for through-hole PCB mounting. It is not a surface-mount device. The mechanical data specifies matte tin-plated leads compliant with J-STD-002 for wave and reflow soldering, but lead geometry and body design require hole placement and wave soldering or hand-soldering. No SMD variant (e.g., KBU402G-SMT) exists in the official Taiwan Semiconductor ordering matrix.

What is the thermal resistance from junction to ambient (R_θJA) for the KBU402G?

The KBU402G has a typical junction-to-ambient thermal resistance (R_θJA) of 19°C/W, as published in the Thermal Performance section of the datasheet. This value assumes standard JEDEC test conditions (single-layer 1 in² copper pad, no heatsink). Actual R_θJA improves with larger PCB copper areas or external heatsinking - e.g., adding 2 in² of 2-oz copper reduces R_θJA to approximately 12°C/W.