This part is a kind of semiconductor called AP3105.

Function of this product has COST EFFECTIVE GREEN PWM CONTROLLER.

Manufacturers : Diodes

Image and pinout :

Some of the text within the PDF file :

A Product Line of Diodes Incorporated AP3105/V/L/R COST EFFECTIVE GREEN PWM CONTROLLER Description Pin Assignments The AP3105/V/L/R is a low startup current, current mode PWM controller with green-mode power-saving operation. The PWM switching frequency at normal operation is set with 65kHz typically and the dithering of frequency will also improve the EMI feature. When the load decreases, the frequency will reduce and when at a very low load, the IC will enter the „burst mode‟ to minimize switching loss. About 20kHz frequency switching is to avoid the audible noise as well as reducing the standby loss. The skip mode point can be adjusted through the external resistor connected to the current sense resistor. The AP3105/V/L/R features a lot of functions such as the LeadingEdge Blanki [ ... ]

AP3105 PDF Datasheet Download