This part is a kind of semiconductor called STR-W6756.

Function of this product has Universal-Input / 140W Off-Line Quasi-Resonant Flyback Switching Regulator.

Manufacturers : Allegro MicroSystems

Image and pinout :

Some of the text within the PDF file :

g n i h tors c t i a Sw egul R STR-W6756 Universal-Input/140 W Off-Line QuasiResonant Flyback Switching Regulator The STR-W6756 is a quasi-resonant regulator specifically designed to satisfy the requirements for increased integration and reliability in switch-mode power supplies. It incorporates a primary control and drive circuit with an avalanche-rated power MOSFET. The regulator exhibits only low-level high-frequency EMI noise because of soft switching of the MOSFET close to ground (bottom point). A bottom-skip function minimizes an increase of operational frequency during light loads to improve system efficiency over the entire load range. Covering the power range from below 240 watts for a 230 VAC input, or 140 watts for a universal input (85 to 264 VAC), this device can be used in [ ... ]

STR-W6756 PDF Datasheet Download