40 A RMS, 600 V — Snubberless™ Alternistor for inductive AC loads
The STMicroelectronics T4050-6PF is a Snubberless™ Alternistor triac rated for 40 A RMS on-state current and 600 V off-state voltage, housed in a TO-3PF through-hole package. It is designed for AC power switching where inductive loads (motors, transformers, solenoids) generate high dV/dt stress.
Surge handling and thermal limits
Non-repetitive surge current is rated at 420 A for 50 Hz and 400 A for 60 Hz half-cycle, giving headroom for motor start-up and capacitive inrush. The TO-3PF full-pack package isolates the tab, simplifying heatsink mounting without an insulating pad.
Gate drive and holding current
Maximum gate trigger current is 50 mA, with a maximum gate trigger voltage of 1.3 V, compatible with standard logic-level drivers or optocoupler outputs. The maximum holding current of 85 mA ensures the triac latches on cleanly with moderate load currents and does not drop out during load transients.