Through-hole alternistor for 220 VAC mains switching
The ST BTA24-800CWRG is a Snubberless alternistor triac in a TO-220-3 through-hole package, rated for 800 V off-state voltage and 25 A RMS on-state current.
Gate trigger and hold current — drive requirements
Maximum gate trigger current is 35 mA at a 1.3 V gate trigger voltage. This is a moderate drive requirement; a standard optocoupler or a small-signal transistor can drive it directly. The 50 mA maximum hold current ensures the triac latches on once triggered and does not drop out during the zero-cross of a lightly loaded inductive circuit.
Surge capability and thermal margin
Non-repetitive surge current rating is 250 A at 50 Hz and 260 A at 60 Hz. This surge rating covers inrush from motor start-up or lamp cold-filament loads. The 25 A RMS continuous rating at 125°C junction temperature gives headroom for a 15–20 A load with derating for ambient temperature inside an enclosed panel.