STMicroelectronics T4050-6PF

Overview

T4050-6PF from STMicroelectronics is a 40 A RMS, 600 V blocking voltage Snubberless™ Triac in TO-3PF insulated package, optimized for phase-angle control and ON/OFF switching in high-surge industrial loads. It delivers 400 A non-repetitive surge current, 1000 V/μs dV/dt immunity, and UL1557-certified 2.5 kV insulation - enabling robust operation in HVAC actuators, motor soft starters, and SMPS inrush limiters.

For engineers reviewing the T4050-6PF datasheet, T4050-6PF pinout, T4050-6PF application, or T4050-6PF equivalent, key selection criteria include verified snubberless commutation margin (dI/dt)_c = 25.1 A/ms, gate trigger current ≤50 mA at 125 °C, thermal resistance R_th(j–c) = 1.45 °C/W, and ECOPACK®2 RoHS/HF compliance.

Technical Context

This Triac operates bidirectionally across all four quadrants with guaranteed latching current ≤70 mA (QI/QIII) and holding current ≤85 mA at T_j = 125 °C. Its static dV/dt immunity exceeds 1000 V/μs without external snubbers, supported by dynamic commutation capability (dI/dt)_c ≥25.1 A/ms under snubberless conditions.

The device uses a planar passivated silicon structure with optimized gate geometry to sustain repetitive 600 V blocking (V_DRM/V_RRM) and 700 V non-repetitive surge (V_DSM/V_VRSM). Junction-to-case thermal resistance of 1.45 °C/W enables 40 A RMS conduction at T_c = 76 °C without forced cooling.

Key Specifications

Pinout & Package

Package: TO-3PF - full-plastic insulated through-hole package with UL94 V0 epoxy, lead-free and halogen-free construction, 5.2 g mass, and recommended mounting torque of 0.8 N·m (max 1.0 N·m).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BTB24-600CW and Z0409MN, the T4050-6PF provides superior surge handling (400 A vs. ≤200 A), certified isolation (2.5 kV), and verified snubberless operation - making it the only choice for UL-listed industrial equipment requiring long-term reliability under high-dI/dt transients.

Availability

T4050-6PF is available at Aetrix Electronics and suitable for HVAC actuator control, solid-state relay manufacturing, and motor soft starter design requiring stable component supply and long-lifecycle support.

Supply support for T4050-6PF 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 T4050-6PF belongs to ST's Snubberless™ Triac product line, engineered specifically for high-immunity AC power control in harsh industrial environments where reliability under voltage transients and thermal stress is non-negotiable.

FAQ

What is the maximum allowable gate trigger current for reliable turn-on across all temperatures?

The peak gate current must not exceed 8 A (tp = 20 µs, T_j = 125 °C), but reliable triggering is achieved with ≤50 mA DC or pulse current at 25 °C - de-rating to ≤35 mA is recommended above 100 °C per Figure 5 in DS12857. Exceeding I_GT max risks gate junction damage without improving turn-on speed.

Can T4050-6PF be used without a heatsink in free-air convection?

No. At ambient temperature of 50 °C, maximum RMS current drops to ~1.5 A (Figure 3); sustained 40 A operation requires case temperature ≤76 °C, mandating a heatsink with thermal resistance ≤1.45 °C/W. Without heatsinking, the device self-destructs within seconds at rated current due to thermal runaway.

Is the TO-3PF package compatible with standard TO-220 heatsinks?

No. TO-3PF has a unique footprint: 44.4 mm × 23.2 mm body width/length, 15.7 mm height, and 3.8 mm mounting hole spacing (R dimension). Standard TO-220 clips or thermal pads will not align. ST recommends dedicated TO-3PF-compatible heatsinks (e.g., Fischer SK 100 series) with M3.5 screw compatibility.

Does "Snubberless™" mean no external components are ever needed?

Snubberless™ certifies operation without snubbers under defined conditions: dV/dt ≤1000 V/μs, (dI/dt)_c ≥25.1 A/ms, and inductive load L/R ≤10 ms. For highly reactive loads (e.g., transformer primaries) or environments exceeding 1.2 kV/μs transients, a minimal RC snubber (100 Ω + 100 pF) remains advisable per application note AN437.