Taiwan Semiconductor Corporation KBU804G

Overview

KBU804G from Taiwan Semiconductor is a 8A, 400V repetitive peak reverse voltage (VRRM) glass-passivated standard bridge rectifier in KBU package, featuring 200A surge current capability, 1.1V max forward voltage at 8A/25°C, and <5µA reverse leakage at 25°C - used in AC/DC front-end stages of compact switching mode power supplies.

For engineers reviewing the KBU804G datasheet, KBU804G pinout, KBU804G application, or KBU804G equivalent, key selection considerations include VRRM derating for line-voltage transients, thermal resistance (R_θJA = 18°C/W), junction temperature limits (–55°C to +150°C), and UL recognition (E-326243) for safety-compliant designs.

Technical Context

The KBU804G integrates four silicon diodes in a single-phase full-wave bridge configuration with quad internal layout, enabling direct AC-to-DC conversion without external interconnects. Its glass-passivated junction ensures stable reverse characteristics across temperature and long-term reliability under repeated surge stress.

Designed for PCB mounting with matte tin-plated leads (J-STD-002 compliant), the device supports high-density layouts and meets UL 94V-0 flammability and JESD201 Class 1A whisker resistance requirements - critical for industrial and lighting applications operating near thermal limits.

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 GBU8K and W04M, the KBU804G delivers optimal balance of 8A continuous capacity, 18°C/W thermal performance, and compact KBU footprint - making it preferred for space-constrained 45–65W SMPS designs requiring UL recognition and industrial-grade reliability.

Availability

KBU804G is available at Aetrix Electronics and suitable for switching mode power supplies, LED lighting drivers, and industrial PLC power modules requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for KBU804G 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 electronics and industrial markets since 1979.

The KBU804G belongs to TSC's standard bridge rectifier product line, engineered for high-reliability AC/DC conversion in cost-sensitive, thermally demanding applications such as consumer adapters and commercial lighting systems.

FAQ

What is the maximum allowable case temperature for continuous operation of the KBU804G?

The KBU804G is rated for continuous operation with case temperature up to 75°C at full 8A average forward current. Exceeding this requires derating per the Forward Current Derating Curve in the datasheet. Thermal design must ensure junction temperature remains ≤150°C under worst-case ambient and power dissipation conditions. The KBU804G's R_θJC = 3°C/W enables effective heatsinking when mounted to metal chassis or dedicated thermal pads.

Does the KBU804G support RoHS-compliant assembly processes?

Yes, the KBU804G is RoHS compliant and features matte tin-plated leads qualified to J-STD-002 for solderability. It contains no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above threshold limits. The molding compound meets UL 94V-0 flammability standards, and the device passes JESD201 Class 1A whisker testing - confirming suitability for lead-free reflow profiles and long-term reliability in automated SMT lines.

How does the KBU804G's 400V VRRM rating translate to usable AC input voltage range?

The KBU804G's 400V VRRM supports AC input voltages up to 280V RMS (since √2 × 280V ≈ 396V peak). This covers universal input (85–265V AC) with margin and is commonly used in 230V AC-only lighting and industrial supplies. For 305V AC-rated equipment, a higher-voltage variant like KBU806G (800V) is required. The KBU804G's rating ensures robustness against line surges up to 400V peak without avalanche breakdown.

Can the KBU804G be used in place of a discrete diode bridge built with four 1N4007s?

Yes, the KBU804G replaces four 1N4007 diodes in a single-phase bridge configuration, offering identical 400V VRRM and superior 8A/200A ratings versus 1A/30A for each 1N4007. It provides tighter parameter matching, reduced PCB area, improved thermal coupling, and UL recognition - unlike discrete solutions. However, pinout differs: KBU804G uses dedicated AC1/AC2/+/- terminals, requiring layout update from individual diode footprints.

What is the typical junction capacitance of the KBU804G and how does it affect EMI performance?

The KBU804G exhibits 400 pF typical junction capacitance per diode at 1 MHz and 4.0V reverse bias. This capacitance contributes to high-frequency common-mode noise generation during reverse recovery, especially in high-dV/dt SMPS environments. To mitigate EMI, layout best practices include minimizing loop area between AC inputs and bulk capacitor, adding RC snubbers across AC terminals if needed, and using Y-capacitors referenced to earth ground - all validated in designs using the KBU804G in 65W USB-C PD adapters.