This part is a kind of semiconductor called BP3123.

Function of this product has High Precision PSR Constant Current LED Driver.

Manufacturers : BPS

Image and pinout :

Some of the text within the PDF file :

BP3123 High Precision PSR Constant Current LED Driver Description The BP3123 is a high precision primary-side feedback and regulation controller for LED lighting, it operates in constant current control mode and is designed to work in inductor current discontinuous conduction mode and especially suitable for flyback convertor under universal input. The output power of system is recommended to less than 5W. The BP3123 integrates 650V power MOSFET. Since adopting primary sense and feedback control technology, the secondary sense and feedback circuit is eliminated. The loop compensation components are also removed while maintaining stability overall operating conditions. It uses patent pending source driver architecture and demagnetization sensing technology, the operating current is very lo [ ... ]

BP3123 PDF Datasheet Download