Taiwan Semiconductor Corporation KBU406G

Overview

KBU406G from Taiwan Semiconductor is a 4A, 800V repetitive peak reverse voltage (V_RRM) standard bridge rectifier in KBU package, featuring glass-passivated junctions, 150A surge capability (I_FSM), and <1.1V forward voltage at 4A/25°C. It serves as the AC-to-DC conversion stage in compact off-line power supplies.

For engineers reviewing the KBU406G datasheet, KBU406G pinout, KBU406G application, or KBU406G equivalent, key selection criteria include V_RRM margin for line-voltage transients, thermal resistance (R_θJC = 4°C/W), I₂t rating (93 A²s), and UL recognition (E-326243) for safety-compliant designs.

Technical Context

The KBU406G integrates four silicon diodes in a single-phase full-wave bridge configuration with quad-anode/cathode topology. Its glass-passivated junction ensures stable leakage (<5 µA @ 25°C, <500 µA @ 125°C) and high reliability under thermal cycling.

Designed for PCB mounting with matte tin-plated leads (J-STD-002 compliant), it delivers 19°C/W junction-to-ambient thermal resistance and supports 0.56 N·m maximum mounting torque without mechanical damage to the KBU molded case.

Key Specifications

Pinout & Package

Package: KBU - Molded plastic case with 4 axial leads (2 AC inputs, 1 +DC, 1 –DC), UL 94V-0 rated, 7.2 g weight, polarity marked on body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with GBU4K and W04M, the KBU406G offers superior thermal resistance, UL recognition, and higher surge robustness-making it optimal for certified, high-reliability AC/DC front ends where voltage margin and safety documentation are mandatory.

Availability

KBU406G 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 extended lifecycle planning.

Supply support for KBU406G 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 industrial and consumer markets since 1979.

The KBU series was developed specifically for high-reliability, cost-optimized AC/DC front-end rectification in compact off-line power supplies-emphasizing safety certification, surge resilience, and thermal efficiency.

FAQ

What is the peak repetitive reverse voltage rating of the KBU406G?

The KBU406G has a peak repetitive reverse voltage (V_RRM) rating of 800 V. This value is explicitly specified in the Absolute Maximum Ratings table for the KBU406G variant and defines the maximum reverse voltage the device can block repeatedly without breakdown. It is selected to provide sufficient margin above 230 VAC RMS (≈325 V peak) and transient overvoltages in universal-input power supplies.

Does the KBU406G require a heatsink in typical 4A operation?

The KBU406G does not require an external heatsink for continuous 4A operation at ambient temperatures ≤45°C with adequate PCB copper area (≥25 cm² 2 oz copper) and free airflow. Its R_θJC of 4°C/W and R_θJA of 19°C/W allow thermal dissipation via the leads and case. However, in enclosed or high-temperature environments (>60°C ambient), direct mounting to a metal chassis using the specified 0.56 N·m torque is recommended to maintain T_J ≤150°C.

Is the KBU406G RoHS compliant and lead-free?

Yes, the KBU406G is RoHS compliant per EU Directive 2011/65/EU and uses lead-free matte tin-plated leads that meet J-STD-002 solderability requirements. The molding compound is UL 94V-0 rated, and the entire construction avoids restricted substances including lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE. Compliance is confirmed in the official Taiwan Semiconductor product documentation (Version J2103).

What is the marking code printed on the KBU406G device body?

The KBU406G is marked with "KBU406G" followed by a date code (YWW format) and factory code (e.g., "F") on the top surface of the KBU package. This marking aligns with the ordering code defined in the datasheet and distinguishes it from other members of the KBU401G–KBU407G family, ensuring correct identification during assembly and inspection.

How does the KBU406G compare to the KBU404G in terms of voltage rating and application suitability?

The KBU406G has a V_RRM of 800 V, while the KBU404G is rated at 400 V. This makes the KBU406G suitable for 230/277 VAC systems with higher transient immunity, whereas the KBU404G is limited to 120 VAC or SELV applications. Both share identical I_F, I_FSM, thermal, and package characteristics-but substituting KBU404G for KBU406G in 230 VAC designs risks reverse breakdown and field failure.