STMicroelectronics T835T-8T

Overview

T835T-8T from STMicroelectronics is a snubberless, medium-current, three-quadrant Triac in TO-220AB package, rated for 8 A RMS on-state current and 800 V repetitive peak off-state voltage (VDRM/VRRM), with 35 mA gate trigger current (IGT). It delivers high static/dynamic commutation performance and operates across -40 °C to +150 °C junction temperature, enabling reliable AC line switching in motor control and lighting circuits without external snubbers when design limits are observed.

For engineers reviewing the T835T-8T datasheet, T835T-8T pinout, T835T-8T application, or T835T-8T equivalent, key selection criteria include dV/dt immunity (≥1000 V/µs at 150 °C), critical di/dt capability (≥4 A/ms at 150 °C), snubberless operation validation, and ECOPACK2-compliant through-hole packaging for industrial thermal management.

Technical Context

This Triac supports phase-angle and zero-crossing AC switching in single-phase systems, leveraging three-quadrant triggering (Quadrants I, II, and III) to reduce gate drive complexity and improve noise immunity. Its high dV/dt (1000–2000 V/µs) and (di/dt)_c (4–8 A/ms) ratings ensure robust turn-off under inductive load transients and voltage surges up to 900 V non-repetitive peak (VDSM/VRSM).

The device's low on-state voltage (V_T ≤ 1.55 V at 25 °C; V_TO ≤ 0.85 V at 150 °C) and dynamic resistance (R_d ≤ 57 mΩ) minimize conduction losses, while its 1.9 °C/W junction-to-case thermal resistance enables direct heatsink mounting in compact 8 A power switching applications.

Key Specifications

Pinout & Package

TO-220AB package: insulated case, vertical lead orientation, 3-pin through-hole mount with metal tab (A2) electrically connected to main terminal. Designed for mechanical stability, thermal transfer via heatsink interface, and UL94 V0 halogen-free epoxy compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BT139-800E and MAC8QY8, the T835T-8T offers superior snubberless operation assurance, tighter thermal resistance, and verified three-quadrant gate drive simplicity-making it optimal for space-constrained, thermally demanding motor and lighting controls where reliability and component count matter.

Availability

T835T-8T is available at Aetrix Electronics and suitable for motor control, lighting dimming, and home appliance load switching requiring stable component supply and long-term industrial lifecycle support.

Supply support for T835T-8T 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, MCU, power, and sensing solutions for industrial, automotive, and consumer markets.

The T835T-8T belongs to ST's "Snubberless Triacs" product line, engineered specifically for high-reliability, low-BOM-count AC power control in cost-sensitive, thermally constrained applications such as white goods and building automation.

FAQ

Is the T835T-8T truly snubberless in all applications?

Yes-when operated within its validated limits: dV/dt ≤ 1000 V/µs at 150 °C, (di/dt)_c ≥ 4 A/ms, and peak voltage ≤ 900 V. ST's DS9625 Rev 6 explicitly certifies snubberless operation for resistive and inductive loads meeting these constraints, eliminating the need for RC networks in properly designed circuits.

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

The datasheet specifies IT(RMS) = 8 A at Tc = 131 °C. This means the case (heatsink interface) must be maintained at or below 131 °C under full-load conditions. Exceeding this temperature requires linear derating per Figure 2, reaching 0 A at ~155 °C case temperature.

Can the T835T-8T replace a four-quadrant Triac in existing designs?

It can replace four-quadrant Triacs only if the gate driver supports triggering in Quadrants I, II, and III-and does not require QIV (negative gate pulse with respect to A2). The T835T-8T omits QIV operation, simplifying drive circuitry but limiting compatibility with legacy QIV-dependent controllers.

Does the TO-220AB package provide electrical isolation between the tab and pins?

No-the metal tab is internally connected to A2 (MT2) and is not electrically isolated. For isolated mounting, a mica washer or silicone pad with appropriate dielectric rating must be used between tab and heatsink, or an alternative like MAC8QY8 (isolated-tab TO-220) should be selected.