STMicroelectronics BTA08-400BRG

Overview

BTA08-400BRG from STMicroelectronics is a snubberless, logic-level triac rated for 8 A RMS on-state current and 400 V repetitive peak off-state voltage (VDRM/VRRM), designed for AC phase control and switching in mains-powered loads. It features 5 mA maximum gate trigger current (IGT), 1.2 V maximum gate trigger voltage (VGT), and 2500 VRMS insulated tab compliance with UL E81734 - enabling direct microcontroller interfacing and safe operation on inductive loads such as motor starters and heating regulators.

For engineers reviewing the BTA08-400BRG datasheet, BTA08-400BRG pinout, BTA08-400BRG application, or BTA08-400BRG equivalent, key selection criteria include its snubberless commutation performance (dV/dt = 400 V/µs min), low IGT compatibility with 3.3 V/5 V logic, insulated TO-220AB package, and thermal resistance Rth(j-c) = 2.5 °C/W - critical for compact industrial AC control designs.

Technical Context

This triac operates in three quadrants (I, II, III) with snubberless capability, enabling reliable commutation on inductive loads without external RC snubbers. Its dV/dt immunity of 400 V/µs (min) at Tj = 125 °C and critical rate of decrease of main current (dl/dt)c ≥ 7 A/ms (at dV/dt = 10 V/µs) ensure robust turn-off under reactive load conditions.

The device integrates an internal ceramic-insulated tab rated at 2500 VRMS per UL E81734, supporting safe mounting to heatsinks without additional isolation hardware. Gate sensitivity is optimized for direct drive from microcontrollers: IGT ≤ 5 mA and VGT ≤ 1.2 V at 25 °C, with guaranteed minimum IGT at 5% of max across temperature.

Key Specifications

Pinout & Package

Package: TO-220AB Insulated - thermally conductive but electrically isolated tab (2500 VRMS), 3-pin through-hole mount with standard 2.54 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triac switching applications.

Compared with BTA08-400BRG, BTA08-400SWRG trades lower gate sensitivity for broader drive compatibility, while T835-600H offers superior thermal performance and higher voltage rating in a surface-mount format - but forfeits built-in isolation and requires added safety measures in high-voltage chassis designs.

Availability

BTA08-400BRG is available at Aetrix Electronics and suitable for motor speed control, heating regulation, light dimming, and static relay replacement requiring stable component supply across industrial automation, appliance, and building control programs.

Supply support for BTA08-400BRG 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, and discrete devices for industrial, automotive, and consumer markets.

The BTA series belongs to ST's high-reliability snubberless triac product line, engineered specifically for robust AC switching in inductive and resistive loads - emphasizing gate sensitivity, commutation immunity, and safety-certified packaging.

FAQ

What is the maximum junction temperature for continuous operation?

The BTA08-400BRG has an operating junction temperature range of –40 °C to +125 °C. Continuous operation at 8 A RMS requires maintaining case temperature ≤100 °C, supported by its 2.5 °C/W junction-to-case thermal resistance and insulated TO-220AB package.

Does this triac require a heat sink in typical 8 A applications?

Yes - at 8 A RMS, power dissipation reaches ~12.5 W (based on VTM = 1.55 V). With Rth(j-c) = 2.5 °C/W, a 31.3 °C rise above case temperature occurs; therefore, a heatsink maintaining Tc ≤100 °C is mandatory for sustained operation per datasheet derating curves.

Can BTA08-400BRG be used with zero-crossing detection circuits?

Yes - its 5 mA IGT and 1.2 V VGT allow reliable triggering from standard zero-crossing optocouplers (e.g., MOC3041) with series 330 Ω gate resistor. The device supports both leading-edge and zero-crossing phase control topologies without modification.

Is the insulated tab rated for continuous 2500 VRMS or only dielectric test voltage?

The 2500 VRMS rating is a certified working voltage per UL file E81734 - not just a one-second dielectric test value. It specifies continuous reinforced insulation between the tab and internal die, permitting direct metal heatsink mounting in Class I appliances and industrial equipment.