4 A RMS, 800 V off-state — Snubberless alternistor for inductive loads
The STMicroelectronics T435-800H is a 4 A RMS Snubberless™ alternistor triac rated for 800 V off-state voltage, designed for switching AC loads without an external snubber network. The Snubberless structure handles high dV/dt during commutation, making it suitable for inductive loads like small motors, solenoids, and transformers where a standard triac would false-trigger. Housed in a through-hole TO-251 (IPAK) package, the device suits compact board-level assemblies where a heatsink can be soldered or clipped to the exposed tab. The single triac configuration simplifies layout for one-phase AC switching.
Gate drive and surge handling — what the trigger currents mean for your circuit
Maximum gate trigger current (Igt) is 35 mA, with a maximum gate trigger voltage (Vgt) of 1.3 V. A logic-level MCU output driving an optocoupler or a small bipolar transistor can fire the gate directly — no high-current driver IC needed. The 35 mA maximum hold current (Ih) means the triac latches on until the load current drops below that threshold near the AC zero-cross. Non-repetitive surge current (Itsm) is 30 A at 50 Hz and 31 A at 60 Hz, covering inrush events from capacitive or filamentary loads. The 800 V off-state rating provides margin on a 230 VAC line (peak ~325 V) and even on 277 VAC (peak ~392 V), reducing risk from mains transients.
RoHS3 compliance is confirmed, covering the EU RoHS exemption framework through 2024.