This part is a kind of semiconductor called BT139-800.

Function of this product has 4Q Triac.

Manufacturers : NXP

Image and pinout :

Some of the text within the PDF file :

TO-220AB BT139-800 4Q Triac 27 September 2013 Product data sheet 1. General description Planar passivated four quadrant triac in a SOT78 (TO-220AB) plastic package intended for use in applications requiring high bidirectional transient and blocking voltage capability and high thermal cycling performance. 2. Features and benefits • High blocking voltage capability • Planar passivated for voltage ruggedness and reliability • Less sensitive gate for high noise immunity • Triggering in all four quadrants 3. Applications • General purpose motor controls • General purpose switching 4. Quick reference data Table 1. Quick reference data Symbol Parameter Conditions VDRM repetitive peak offstate voltage ITSM non-repetitive peak on- full sine wave; Tj(init) = 25 °C; state cur [ ... ]

BT137-600E PDF Datasheet Download