The BT137B-800,118 is a NXP TRIAC. It is a sensitive and standard gate Thyristor device in a 3-pin SOT223 package. This TRIAC has a gate-trigger current of 800 µA, a holding current of 118 A, and a voltagse break down of 420 V. It is used as an AC control device for controlling inrush, as a general on/off switch for medium duties, as a reference for zero cross detect, and for critical load switching.