STMicroelectronics BTA08-400CRG

Overview

BTA08-400CRG from STMicroelectronics is a snubberless, standard-sensitivity (35 mA IGT), 8 A RMS, 400 V repetitive peak off-state voltage triac in insulated TO-220AB package. It delivers high commutation robustness for inductive AC loads and supports phase-control operation with gate-triggering compatible with discrete transistor or optocoupler drivers. It is used in motor speed controllers, heating regulation circuits, and static relays requiring reliable zero-crossing–independent switching.

For engineers reviewing the BTA08-400CRG datasheet, BTA08-400CRG pinout, BTA08-400CRG application, or BTA08-400CRG equivalent, key selection criteria include dV/dt immunity (≥200 V/µs), insulated tab rating (2500 VRMS), latching current (IL ≤ 50 mA), and thermal resistance (Rth(j-c) = 2.5 °C/W) for heatsink-limited industrial designs.

Technical Context

This triac operates in all four quadrants but is optimized as a snubberless device for inductive load commutation, with guaranteed critical dV/dt immunity of ≥200 V/µs at Tj = 125 °C and (dI/dt)c ≥ 5 V/µs under same conditions. Its internal ceramic-insulated tab enables safe mounting to grounded heatsinks without additional isolation hardware.

The device features a low on-state threshold voltage (VTO ≤ 0.85 V at Tj = 125 °C) and dynamic resistance (RD ≤ 50 mΩ), enabling efficient power handling up to 8 A RMS at case temperature ≤100 °C. Gate trigger current is specified at 35 mA max (Quadrants I, II, III) with 1.3 V max gate trigger voltage (VGT).

Key Specifications

Pinout & Package

Insulated TO-220AB package with electrically isolated metal tab rated at 2500 VRMS (UL E81734). Tab connects internally to A2 terminal. Mounting screw torque: 0.55 N·m (recommended), max 0.70 N·m.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BTA08-400CRG, BTA08-400BWRG trades higher gate drive demand for greater noise immunity, while T835-600H sacrifices tab insulation for lower thermal resistance and SMT compatibility-neither is pin-compatible, and both require layout or driver redesign.

Availability

BTA08-400CRG is available at Aetrix Electronics and suitable for motor speed control, heating regulation, static relay implementation, and light dimmer designs requiring stable component supply across industrial production cycles.

Supply support for BTA08-400CRG 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, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

BTA08-400CRG belongs to ST's high-reliability snubberless triac product line, engineered specifically for robust AC power control in thermally demanding, inductive-load applications without external protection circuitry.

FAQ

What is the maximum allowable case temperature for continuous 8 A RMS operation?

The BTA08-400CRG is rated for 8 A RMS continuous conduction at TC = 100 °C when mounted on an insulated heatsink with proper torque (0.55 N·m). Exceeding this temperature reduces IT(RMS) linearly per Figure 2 in DS2114; at TC = 110 °C, derating to ~7.2 A is required.

Does the insulated tab require additional dielectric hardware during heatsink mounting?

No additional dielectric hardware is required-the TO-220AB Ins. package integrates a certified ceramic insulator under the tab, rated for 2500 VRMS per UL file E81734. However, mechanical shoulder washers or non-conductive mounting kits are recommended to prevent tab damage and ensure uniform pressure distribution.

Can BTA08-400CRG be driven directly by a 3.3 V microcontroller GPIO?

No-its maximum gate trigger current is 35 mA at 12 V with 33 Ω load, and VGT is up to 1.3 V. A 3.3 V GPIO cannot source sufficient voltage or current; a buffer stage (e.g., BC847 NPN or MOC3023 optocoupler) is mandatory to meet IGT and VGT requirements reliably across temperature and unit variation.

Is a snubber circuit required for inductive loads like solenoids or transformers?

No snubber is required due to its snubberless design: dV/dt immunity ≥200 V/µs and (dI/dt)c ≥5 V/µs guarantee reliable commutation without false triggering. This is validated for standard inductive loads per ST's application note AN437, though extreme L/R ratios may warrant empirical validation.