800 V off-state, 16 A RMS — the load ratings that size the snubber and heatsink
The BTB16-800BRG is a standard triac from STMicroelectronics rated for 800 V off-state voltage and 16 A RMS on-state current. These two numbers define the load it can switch — a 230 VAC motor, heater, or lighting bank — and the voltage margin you need for line transients. The 160 A / 168 A non-repetitive surge rating (50/60 Hz) tells you the fuse or breaker must clear before the junction sees a second cycle at that level.
50 mA gate trigger and holding current — matching the driver and the load
Gate trigger current (Igt) is 50 mA max, with a 1.3 V max gate trigger voltage. That is a standard-level gate — it needs a driver that can source 50 mA, not a sensitive-gate part. The 50 mA holding current (Ih) means the triac will drop out of conduction if the load current falls below 50 mA; for a resistive load that is rarely an issue, but for an inductive load with a low holding-current requirement you may need a snubber or a different triac grade.
TO-220 through-hole — the thermal and mechanical anchor
The TO-220-3 package (supplier device package TO-220) is a through-hole part with a metal tab that bolts to a heatsink. The tab is the thermal path — the junction-to-case thermal resistance determines the heatsink size.
It is ROHS3 compliant.