Taiwan Semiconductor Corporation TBS408

Overview

TBS408 from Taiwan Semiconductor is a 4A, 800V repetitive peak reverse voltage (V_RRM) standard quad bridge rectifier in TBS package, featuring glass-passivated junctions, UL recognition (E-326854), and J-STD-020 Level 1 moisture sensitivity - deployed in AC/DC front-end stages of compact switching mode power supplies.

For engineers reviewing the TBS408 datasheet, TBS408 pinout, TBS408 application, or TBS408 equivalent, key selection criteria include its 800V V_RRM, 110A I_FSM surge rating, 0.95V max forward voltage at 4A/25°C, 13°C/W R_θJL, and RoHS/halogen-free compliance for high-reliability industrial adapter designs.

Technical Context

The TBS408 integrates four silicon diodes in a single-phase full-wave bridge configuration with common-cathode and common-anode terminals externally accessible. Its glass-passivated junction ensures stable reverse leakage (<2 µA @ 25°C, <200 µA @ 125°C) and robust thermal performance under pulsed load conditions.

Thermal design relies on low junction-to-lead resistance (13°C/W) when mounted on a 16 mm × 16 mm copper pad PCB; electrical behavior is characterized per diode - including 38 pF junction capacitance at 1 MHz/4 V and forward voltage drift from 0.95 V (25°C) to 0.84 V (125°C) at 4 A.

Key Specifications

Pinout & Package

Package: TBS - molded plastic body with matte tin-plated leads, UL 94V-0 rated, polarity marked on top surface, weight ≈0.220 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with GBU4K and MB10F, the TBS408 delivers optimal balance of compact TBS footprint, 13°C/W R_θJL, and 0.95 V V_F - making it ideal for thermally constrained, high-volume adapter and lighting applications where board space and thermal management are critical.

Availability

TBS408 is available at Aetrix Electronics and suitable for switching mode power supplies, LED lighting drivers, and USB-C PD adapters requiring stable component supply, consistent parametric performance, and full RoHS/halogen-free compliance.

Supply support for TBS408 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 protection markets since 1979.

The TBS series bridges are engineered specifically for high-efficiency, surface-mount AC/DC front-end rectification in space- and thermal-constrained consumer and industrial power supplies.

FAQ

What is the maximum repetitive peak reverse voltage (V_RRM) of the TBS408?

The TBS408 has a specified V_RRM of 800 V, verified per Taiwan Semiconductor's B2103 datasheet. This rating ensures reliable operation under peak line voltages up to 560 V_RMS, with appropriate safety margin for transient surges. The TBS408 is part of the TBS406–TBS410 family, where V_RRM scales by model number (600 V, 800 V, 1000 V). Always confirm layout clearance and creepage distances match this voltage class.

Does the TBS408 require pre-baking before reflow soldering?

No, the TBS408 does not require pre-baking. It is rated J-STD-020 Moisture Sensitivity Level 1, meaning it has unlimited floor life at ≤30°C/60% RH and can be placed directly into reflow without moisture mitigation steps. This simplifies SMT line logistics and eliminates risk of popcorning during thermal cycling - a key advantage confirmed in the official TSC documentation for the TBS408.

What is the forward voltage (V_F) of the TBS408 at full rated current?

At 4 A and 25°C junction temperature, the TBS408 exhibits a maximum forward voltage of 1.00 V per diode, with typical value of 0.95 V. At elevated temperature (125°C), V_F drops to 0.84 V max due to negative temperature coefficient - a characteristic confirmed in the Electrical Specifications table of the TBS408 datasheet. This behavior reduces conduction loss under thermal stress.

Is the TBS408 certified for safety standards like UL?

Yes, the TBS408 is UL Recognized under File # E-326854, covering the entire TBS406–TBS410 series. This certification applies to the device's construction, flammability (UL 94V-0 molding compound), and long-term reliability under rated electrical and thermal stress. UL recognition supports faster end-product safety approvals without requiring additional component-level investigation for the TBS408.

How does the thermal resistance of the TBS408 compare to industry-standard bridge packages?

The TBS408 specifies R_θJL = 13°C/W (junction-to-lead), measured on a 16 mm × 16 mm Cu pad PCB - significantly lower than typical GBU or KBPC packages (e.g., GBU4K: ~25°C/W). This enables more efficient heat transfer to the PCB, reducing reliance on external heatsinks. The value is validated in the Thermal Performance section of the TBS408 datasheet and reflects optimized leadframe design within the TBS package.