STMicroelectronics T635T-8FP

Overview

T635T-8FP from STMicroelectronics is a 6 A, 800 V Snubberless™ Triac in TO-220FPAB package, designed for AC line switching and phase-angle control without external snubber circuits when operated within datasheet limits. It delivers high static/dynamic commutation (dV/dt ≥ 2000 V/µs at 125 °C, (dI/dt)c ≥ 6 A/ms), supports three-quadrant triggering, and provides UL-certified 2 kV insulation for motor control, lighting, and overvoltage crowbar protection.

For engineers reviewing the T635T-8FP datasheet, T635T-8FP pinout, T635T-8FP application, or T635T-8FP equivalent, key selection criteria include rated rms current (6 A), blocking voltage (800 V), gate trigger current (35 mA max), commutation robustness (dV/dt and (dI/dt)c), and UL-rated isolation - all critical for reliable AC load switching in industrial and appliance designs.

Technical Context

The T635T-8FP is a three-quadrant, medium-current triac optimized for snubberless operation in resistive and inductive AC loads. Its high dV/dt immunity (2000 V/µs min at 125 °C) and critical (dI/dt)c (6 A/ms min at 125 °C) enable stable turn-off under fast-reapplied voltage transients common in motor and transformer-driven circuits.

It features symmetric gate sensitivity across Quadrants I, II, and III (IGT ≤ 35 mA), low on-state voltage (VT ≤ 1.55 V at 8.5 A), and thermal resistance Rth(j-c) = 4.5 °C/W - enabling direct heatsink mounting for sustained 6 A rms conduction at TC = 117 °C.

Key Specifications

Pinout & Package

Package: TO-220FPAB - Insulated plastic package with integral heatsink tab, lead-free, UL94 V0 epoxy, 2.0 g weight, and recommended mounting torque of 0.4–0.6 N·m.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BTB16-800CW and T635T-800G, the T635T-8FP uniquely combines snubberless operation, UL-certified 2 kV isolation, and three-quadrant gate control in a single 6 A device - making it optimal for compact, safety-certifiable, and component-count-sensitive AC switching designs.

Availability

T635T-8FP is available at Aetrix Electronics and suitable for motor control circuits, lighting dimmers, and small home appliance power switching requiring stable component supply and long-term manufacturability.

Supply support for T635T-8FP 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The T635T-8FP belongs to ST's Snubberless™ Triac product line, engineered specifically for simplified, reliable, and safety-compliant AC power control in cost-sensitive, space-constrained applications.

FAQ

Is the T635T-8FP truly snubberless in all applications?

No - snubberless operation is guaranteed only when operating conditions stay within the dV/dt and (dI/dt)c limits defined in the datasheet (e.g., dV/dt ≤ 2000 V/µs at 125 °C, (dI/dt)c ≥ 6 A/ms). Inductive loads exceeding these limits require an external RC snubber to prevent false triggering or commutation failure.

What does "three-quadrant" mean for the T635T-8FP's gate operation?

Three-quadrant operation means the device triggers reliably with gate pulses applied between G–A1 (Quadrants I and II) or G–A2 (Quadrant III), excluding Quadrant IV (G–A2 with reverse polarity). This reduces gate drive complexity and eliminates need for negative gate voltage in most AC phase-control topologies.

Can the T635T-8FP replace a standard 6 A triac like the BTA06-600B?

Yes, but only if the application requires 800 V blocking (vs. BTA06-600B's 600 V), snubberless operation, and UL-rated 2 kV isolation. The T635T-8FP offers higher dV/dt immunity and better commutation margins, but its gate trigger threshold (35 mA max) is higher than BTA06-600B's (≤50 mA), requiring compatible driver strength.

What thermal derating applies when using the T635T-8FP without a heatsink?

Without a heatsink, the device relies on Rth(j-a) = 60 °C/W. At ambient 50 °C, maximum allowable power dissipation is ~1.7 W, limiting IT(rms) to ~1.2 A. For 6 A operation, a heatsink maintaining TC ≤ 117 °C (per datasheet) is mandatory - verified via thermal simulation or empirical measurement.