12 A RMS, 700 V — the load-switching envelope
The BTA12-700SWRG is a logic-level sensitive-gate triac from STMicroelectronics, rated for 12 A RMS on-state current and 700 V off-state blocking voltage — enough headroom to switch 230/277 VAC loads like small motors, heaters, and lighting ballasts without worrying about mains transients punching through. Its gate trigger current is just 10 mA max at 1.3 V max, which means a 3.3 V or 5 V microcontroller GPIO can drive it directly through a current-limiting resistor — no separate driver transistor or optocoupler needed for many designs.
Surge rating and thermal margin
Non-repetitive surge current is 120 A at 50 Hz and 126 A at 60 Hz — that is the peak the die can survive for one half-cycle during a fault or inrush event. Pair it with a fuse or breaker rated below that surge to protect the triac. Hold current is 15 mA max; once triggered, the triac stays latched until the load current drops below that threshold near the AC zero-crossing — typical for standard triac commutation.
Through-hole TO-220 — bench-friendly repair
Housed in a TO-220-3 through-hole package, the BTA12-700SWRG is easy to hand-solder or replace on a repair bench — no hot-air rework needed. The tab is the MT2 terminal; the metal back provides a thermal path to a heatsink if the load current exceeds a few amps continuous. Operating junction temperature range is -40°C to 110°C, covering industrial and outdoor enclosures without derating at the cold end.