Diodes Incorporated T8M35T800UD

Overview

T8M35T800UD from Diodes Incorporated is a glass-passivated, bidirectional silicon thyristor (TRIAC) designed for AC power phase control in mains-connected loads. It features 800V repetitive peak off-state voltage (VDRM/VRRM), 8A RMS on-state current (IT(RMS)), 35mA maximum gate trigger current (IGT), and operates up to +125°C junction temperature. Used in light dimmers, fan speed controllers, and coffee machine heating circuits.

For engineers reviewing the T8M35T800UD datasheet, T8M35T800UD pinout, T8M35T800UD application, or T8M35T800UD equivalent, key selection criteria include quadrant-triggering behavior (QI/QII/QIII only), dV/dt immunity (2000 V/µs at TJ = +125°C), holding current (50 mA max), latching current (50–80 mA), and TO220AB thermal resistance (RθJC = 3.3 °C/W).

Technical Context

This TRIAC operates in three quadrants (I, II, III) only - it does not trigger in Quadrant IV - requiring compatible gate drive circuitry that avoids negative gate-to-MT2 voltage during MT2-positive half-cycles. Its glass passivation ensures stable VDRM/VRRM performance under humidity and thermal stress.

The device supports high dv/dt immunity (2000 V/µs at TJ = +125°C) without snubber, enabling robust commutation in inductive motor control. Thermal design relies on its low RθJC (3.3 °C/W) when mounted on an 80 mm × 80 mm × 1.5 mm copper heatsink, supporting sustained 8A RMS conduction at TJ ≤ +125°C.

Key Specifications

Pinout & Package

Package: TO220AB (Type WX), molded plastic, lead-free, RoHS-compliant, matte tin-plated leads. Weight: ~2.08 g. Internally insulated case rated for functional isolation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TRIAC-based AC power control applications.

Compared with BTB16-800CW and MAC10N800, T8M35T800UD offers optimal balance of 8A capacity, 2000 V/µs dV/dt immunity, and TO220AB insulation - making it ideal for mid-power industrial and appliance controls where snubberless reliability and thermal manageability are critical.

Availability

T8M35T800UD is available at Aetrix Electronics and suitable for light dimming systems, fan speed controllers, coffee machine heating, and power tools requiring stable component supply, RoHS compliance, and automotive-grade change control readiness.

Supply support for T8M35T800UD 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

This part belongs to Diodes' high-voltage, high-reliability TRIAC product line, engineered specifically for robust AC power control in consumer appliances, industrial equipment, and building automation systems operating directly from 100–240VAC mains.

FAQ

What is the maximum gate trigger current (IGT) specification for T8M35T800UD?

The maximum gate trigger current is 35 mA, measured at VAK = 12 V and RL = 100 Ω across all three supported quadrants (QI, QII, QIII). This value is guaranteed at TJ = +25°C and increases slightly at elevated temperatures, as shown in Figure 7 of DS45508 Rev. 3–2. Gate drive circuits must deliver ≥35 mA peak into the specified test load to ensure reliable turn-on under worst-case conditions.

Does T8M35T800UD support Quadrant IV triggering?

No, T8M35T800UD is explicitly rated for triggering in Quadrants I, II, and III only. It does not guarantee turn-on in Quadrant IV (MT2 positive, gate negative), and attempting to operate in this mode may result in inconsistent or failed triggering. Gate drive design must avoid applying negative gate voltage relative to MT1 during MT2-positive half-cycles.

What thermal interface is required to achieve the stated RθJC of 3.3 °C/W?

To achieve the published RθJC of 3.3 °C/W, the device must be mounted on an 80 mm × 80 mm × 1.5 mm copper heatsink using recommended torque (0.5–0.7 N·m) and thermal interface material (e.g., silicone grease or phase-change pad). Mounting on smaller or aluminum heatsinks will increase effective thermal resistance and reduce allowable RMS current.

Is T8M35T800UD qualified for automotive applications per AEC-Q101?

No - while Diodes offers AEC-Q101-qualified TRIACs (e.g., Z0103MN series), T8M35T800UD is not AEC-Q101 certified. It is rated for industrial and consumer applications. For automotive use, contact Diodes' automotive team to request PPAP-capable, IATF 16949-manufactured alternatives with full qualification documentation.