Alternistor triac for inductive loads
The STMicroelectronics BTB12-800CWRG is a Snubberless™ alternistor triac rated for 12 A RMS on-state current and 800 V off-state voltage, housed in a TO-220-3 through-hole package. The alternistor construction means it commutates inductive loads — motors, solenoids, transformers — without the external snubber network a standard triac typically needs, because its internal structure handles the dV/dt stress from the load's back-EMF. The 35 mA gate trigger current and 1.3 V gate trigger voltage are standard for a 12 A class device — a logic-level signal from a microcontroller through a transistor driver will comfortably exceed these thresholds. The 35 mA holding current means the triac stays latched once triggered as long as the load current stays above that floor; below it the device turns off at the next zero-crossing.
Surge and temperature margins
Non-repetitive surge current is 120 A at 50 Hz and 126 A at 60 Hz — this is the peak current the die can withstand for one mains half-cycle without failing. In a motor-start or capacitor-inrush scenario, budget the surge duration and amplitude against this ceiling; a 12 A RMS triac with a 120 A surge rating gives roughly a 10× margin over the continuous rating, which is typical for this class. The junction temperature range spans -40°C to 125°C, covering industrial and outdoor enclosure environments. The 125°C upper limit is the die temperature, not the case — the TO-220 package's thermal resistance to the heatsink determines how much current can be carried at elevated ambient.