This part is a kind of semiconductor called OB2273.
Function of this product has High Performance Current Mode PWM Controller.
Manufacturers : On-Bright
Image and pinout :
Some of the text within the PDF file :
High Performance Current Mode PWM Controller OB2273 GENERAL DESCRIPTION OB2273 is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications. PWM switching frequency at normal operation is internally fixed and is trimmed to tight range. At no load or light load condition, the IC operates in extended ‘burst mode’ to minimize switching loss. Lower standby power and higher conversion efficiency is thus achieved. VDD low startup current and low operating current contribute to a reliable power on startup and low standby design with OB2273. OB2273 offers complete protection coverage with auto-recovery including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), and VDD under vol [ ... ]