This part is a kind of semiconductor called GW6203.

Function of this product has PWM Controller of High-performance Current Mode.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

GW6203 PWM Controller of High-performance Current Mode Product Specification GENERAL DESCRIPTION PWM controller of high-performance current mode is specially designed for AC/DC transformer with high performance and price ratio, which supplies continuous output power of 18W within the range of wide-voltage between 85V and 265V, the output power of peak value can be up to 24W. The combination of optimized reasonable circuit design and bipolar facture technology with high performance and price ratio economizes the whole cost ultimately. The power controller can be applied to the typical fly-back circuit topology so as to form a simple AC/DC transformer. When the output power is lower, IC will reduce the working frequency automatically, therefore, the standby power consumption becomes extreme [ ... ]

GW6203 PDF Datasheet Download