This part is a kind of semiconductor called AX2535.

Function of this product has High Precision CC/CV Primary-Side PWM Power Switch.

Manufacturers : AXElite

Image and pinout :

Some of the text within the PDF file :

AX2535 High Precision CC/CV Primary-Side PWM Power Switch  GENERAL DESCRIPTION AX2535 is a high performance offline PWM Power switch for low power AC/DC charger and adapter applications. It operates in primary-side sensing and regulation. Consequently, the photo-coupler and TL431 could be eliminated. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below. In CC control, the current and output power setting can be adjusted externally by the sense resistor RS at CS pin. In CV control, multi-mode operations are utilized to achieve high performance and high efficiency. In addition, good load regulation is achieved by the built-in cable drop compensation. € Device operates in PFM in CC mode as well at large b Ñ y • load condition [ ... ]

AX2535 PDF Datasheet Download