25 A RMS, 800 V blocking — the workhorse TRIAC for line-voltage loads
The STMicroelectronics BTB24-800BRG is a standard TRIAC in the TO-220-3 through-hole package, rated for 800 V off-state voltage and 25 A RMS on-state current. It handles the AC load switching in motor drives, industrial heaters, lighting dimmers, and solid-state relays where the line voltage is 230 VAC or 400 VAC and the load pulls up to 25 A continuous.
Gate drive and latching — 50 mA Igt, 80 mA Ih
Maximum gate trigger current is 50 mA; maximum holding current is 80 mA. The 1.3 V gate trigger threshold means a standard optocoupler or logic-level driver with a current-limiting resistor can fire the gate. The 80 mA hold current ensures the TRIAC stays latched once conducting — if the load current dips below that threshold near the zero-cross, the device will commutate off, which matters for low-current loads like small fans or transformer primaries.
Surge capability and thermal design
Non-repetitive surge current is 250 A at 50 Hz and 260 A at 60 Hz — this is the peak the die can survive for one cycle during a fuse-clearing event or inrush from a motor start or capacitor bank. The TO-220 tab is the thermal path; a proper heatsink with thermal compound keeps the junction below 125°C at 25 A RMS.
ROHS3 compliant per the supplier listing.