STMicroelectronics T1235H-8I

Overview

T1235H-8I from STMicroelectronics is a 12 A, 800 V insulated triac in TO-220AB package, designed for high-noise immunity AC load switching in constrained thermal environments. It features 150 °C max junction temperature, 2.5 kV RMS insulation rating, and Snubberless™ commutation robustness-enabling compact heater/motor control in home appliances without external snubbers.

For engineers reviewing the T1235H-8I datasheet, T1235H-8I pinout, T1235H-8I application, or T1235H-8I equivalent, key selection criteria include dV/dt immunity (≥2000 V/µs at Tj = 150 °C), (dl/dt)c (≥12 A/ms), gate trigger current (35 mA max), thermal resistance Rth(j-c) (2.1 °C/W), and UL1557-certified insulation.

Technical Context

This triac operates in all four quadrants with enhanced static dV/dt immunity and dynamic turn-off commutation performance, enabled by ST's high-temperature Snubberless technology. Its internal ceramic insulation pad delivers 2.5 kV RMS isolation, and the device sustains full 12 A RMS conduction at case temperatures up to 122 °C.

The T1235H-8I exhibits low on-state voltage (VTM ≤ 1.50 V at 25 °C; VTO ≤ 0.80 V at 150 °C) and low dynamic resistance (RD ≤ 32 mΩ), supporting efficient power delivery in resistive and inductive loads. Leakage current remains below 4.5 mA at 150 °C and VDRM, ensuring stable blocking under elevated thermal stress.

Key Specifications

Pinout & Package

Package: TO-220AB insulated - molded in UL94-V0 halogen-free resin with internal ceramic insulation barrier; lead-free plating; mechanical outline per DS13430 Figure 14.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BTB12-800CW and Q6012LH4, the T1235H-8I uniquely combines 800 V blocking, 2.5 kV insulation, and 2000 V/µs dV/dt at 150 °C-making it the only option qualified for compact, isolated, high-noise AC control in 230 V regions without derating or supplemental protection.

Availability

T1235H-8I is available at Aetrix Electronics and suitable for home appliance motor control, smart AC outlet design, and industrial heater regulation requiring stable component supply and long-term lifecycle support.

Supply support for T1235H-8I 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, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The T1235H-8I belongs to ST's high-temperature Snubberless™ triac product line, engineered specifically for reliable, compact, and isolated AC power control in thermally demanding home appliance and industrial equipment.

FAQ

What is the maximum allowable case temperature for continuous 12 A RMS operation?

The datasheet specifies IT(RMS) = 12 A at Tc = 122 °C (full sine wave, α = 180°). Exceeding this case temperature requires derating per Figure 2. Operation above 122 °C risks thermal runaway due to increased leakage and reduced (dl/dt)c margin, even if junction temperature remains below 150 °C.

Does the T1235H-8I require a heat sink in typical applications?

Yes-though rated for 12 A at Tc = 122 °C, its Rth(j-a) is 60 °C/W in free air. Without a heatsink, ambient temperature must stay below ~30 °C to avoid exceeding Tj(max) = 150 °C. A 15 °C/W heatsink (per Figure 6) is recommended for sustained 12 A operation at 50 °C ambient.

Can the T1235H-8I be used in DC applications?

No-it is a bidirectional AC switch requiring current zero-crossing to commutate. In DC circuits, it latches on after triggering and cannot self-commutate; forced commutation (e.g., series MOSFET or H-bridge) is required, which defeats its design purpose and risks destruction due to uncontrolled I²t accumulation.

Is the gate trigger compatible with standard microcontroller GPIO outputs?

Direct drive is not recommended: IGT(max) = 35 mA exceeds typical GPIO sink/source limits (±20 mA). A buffer stage (e.g., transistor or optotriac like MOC3021) is required to deliver sufficient gate charge while protecting the MCU from transients and ground loop currents.