The STMicroelectronics T835-8G is an 800 V, 8 A RMS Snubberless™ alternistor triac in a D²Pak (TO-263) surface-mount package, part of the T835 series. Its 800 V off-state voltage provides ample margin for 240 VAC mains switching, handling surges and line transients without avalanche breakdown. The 8 A RMS on-state current covers resistive loads like heaters and incandescent lamps up to roughly 1900 W at 240 VAC, and derates for inductive loads such as small motors, solenoids, and transformers where the commutation dV/dt is the limiting factor rather than the steady-state current. The Snubberless™ alternistor construction is the key design differentiator: it commutates inductive loads without an external RC snubber network, saving two passives and board area. The alternistor structure (four-layer NPNP) gives symmetric blocking and better dV/dt immunity than a standard triac in quadrant IV, which is exactly the quadrant that sees the highest commutation stress when switching inductive loads on an AC line. Gate trigger current is 35 mA max with a 1.2 V max gate trigger voltage — these are standard drive levels that a microcontroller GPIO through a series resistor or a simple transistor driver can supply. Hold current is also 35 mA max, meaning the triac latches once triggered and only drops out when the load current falls below that threshold near the AC zero-crossing.
Surge capability and thermal design
Non-repetitive surge current is rated 80 A at 50 Hz and 84 A at 60 Hz — this covers capacitor inrush from power supplies, cold-filament lamp surge, and short-duration mains transients.
Lifecycle and sourcing status
For ongoing production, there is no LTB risk.