The BTA08-600CRG is a standard triac rated for 8 A RMS on-state current (It(RMS)) at a 600 V off-state voltage. That 8 A figure is the continuous sinusoidal current the device can conduct when properly heatsunk — for a resistive load like a heater or incandescent lamp, this is the steady-state limit. For inductive loads (motor, solenoid, transformer), derate for the power factor and the inrush on turn-on; the 80 A / 84 A non-repetitive surge rating (Itsm at 50/60 Hz) covers the first-cycle inrush without damage. The 25 mA gate trigger current (Igt) and 1.3 V gate trigger voltage (Vgt) are the thresholds the drive circuit must deliver to switch the triac on. A microcontroller GPIO driving through a transistor or optocoupler needs to source at least 25 mA into the gate — a logic-level output alone will not do it. The 25 mA holding current (Ih) means the load must draw at least 25 mA to keep the triac latched after the gate signal is removed; below that, the device drops out at the next zero-crossing.
Package and thermal integration
The tab is electrically connected to the MT2 terminal — the heatsink must be electrically isolated or the system ground must account for it.