This part is a kind of semiconductor called STR-G6653.

Function of this product has OFF-LINE QUASI-RESONANT FLYBACK SWITCHING REGULATOR.

Manufacturers : Allegro

Image and pinout :

Some of the text within the PDF file :

Data Sheet 28102.9* STR-G6653 GROUND 3 SUPPLY 4 OSC. FDBK LATCH VIN OCP UVLO OVP TSD 5 OFF-LINE QUASI-RESONANT FLYBACK SWITCHING REGULATOR The STR-G6653 is specifically designed to satisfy the requirements for increased integration and reliability in off-line quasi-resonant flyback converters. This device incorporates the primary control and drive circuit with a discrete avalanche-rated power MOSFET. Cycle-by-cycle current limiting, under-voltage lockout with hysteresis, over-voltage protection, and thermal shutdown protects the power supply during the normal overload and fault conditions. Over-voltage protection and thermal shutdown are latched after a short delay. The latch may be reset by cycling the input supply. Low-current startup and a low-power standby mode selected from t [ ... ]

STR-G6653 PDF Datasheet Download