STMicroelectronics T835H-8T

Overview

T835H-8T from STMicroelectronics is an 8 A, 800 V RMS-rated snubberless triac in TO-220AB package, designed for high-noise immunity AC line switching at up to 150 °C junction temperature. It supports three-quadrant triggering, delivers 2000 V/µs static dV/dt at Tj = 150 °C, and enables compact thermal design in heater and motor control applications.

For engineers reviewing the T835H-8T datasheet, T835H-8T pinout, T835H-8T application, or T835H-8T equivalent, key selection criteria include verified commutation robustness (dl/dt)_c ≥ 8 A/ms at 150 °C, gate trigger current ≤ 35 mA, and junction-to-case thermal resistance of 1.2 °C/W - critical for heatsink-limited industrial and appliance designs.

Technical Context

This triac implements ST's Snubberless high-temperature technology, enabling reliable turn-off under high inductive loads without external snubbers. Its three-quadrant triggering supports simplified gate drive circuits while maintaining noise immunity via guaranteed dV/dt ≥ 2000 V/µs at maximum junction temperature.

The device features a low on-state voltage (V_TM ≤ 1.50 V at 11 A, 25 °C) and dynamic resistance (R_D ≤ 45 mΩ at 150 °C), directly reducing conduction losses in universal motor and resistive load control. Thermal performance is validated with R_th(j–c) = 1.2 °C/W max and R_th(j–a) = 60 °C/W typical (free air).

Key Specifications

Pinout & Package

TO-220AB package with isolated mounting tab (A2), epoxy resin UL94-V0 certified, halogen-free, lead-free plating, 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 line switching applications.

Compared with BT139-800 and MAC8Q-8G, the T835H-8T delivers superior thermal headroom (150 °C vs. 125 °C), higher commutation robustness (8 vs. 5 A/ms), and better noise immunity (2000 vs. 1000 V/µs), making it optimal for sealed, high-reliability appliance designs where heatsink area is constrained.

Availability

T835H-8T is available at Aetrix Electronics and suitable for home appliance motor control, smart AC plug switching, and resistive heater regulation requiring stable component supply across multi-year production cycles.

Supply support for T835H-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, specializing in power management, analog, MEMS, and microcontrollers for industrial, automotive, and consumer markets.

The T835H-8T belongs to ST's Snubberless Triac family, engineered specifically for high-temperature, high-noise immunity AC load control in space- and reliability-constrained appliances and industrial equipment.

FAQ

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

The datasheet specifies IT(RMS) = 8 A at Tc = 139 °C (full sine wave, α = 180°). Operation above this case temperature requires derating per Figure 2; at Tc = 150 °C, RMS current must be reduced to ~7.2 A to maintain thermal safety margins within the 150 °C junction limit.

Does T835H-8T require a heatsink for 8 A operation in free air?

Yes. With R_th(j–a) = 60 °C/W typical (no heatsink), 8 A RMS conduction generates ~12 W power loss (P ≈ I² × R_D + I × V_TM), raising junction temperature by ~720 °C - far exceeding 150 °C. A heatsink with R_th(c–a) ≤ 15 °C/W is mandatory per Figure 6 to avoid thermal runaway.

Can T835H-8T be triggered in Quadrant IV?

No. The device supports triggering only in Quadrants I, II, and III (A2+, G+; A2−, G+; A2−, G−). Quadrant IV (A2+, G−) is not functional - confirmed by gate trigger test conditions in Table 2, which explicitly list only QI–QIII.

Is the TO-220AB mounting tab electrically isolated from the A2 terminal?

Yes. Per ST's TO-220AB mechanical drawing (Figure 14) and package description, the metal tab is internally connected to A2 (MT2) and is not insulated. Electrical isolation must be achieved externally using insulating shoulder washers and bushings when mounting to grounded heatsinks.