This part is a kind of semiconductor called OB2538.

Function of this product has Primary side control high accuracy constant voltage / constant current PWM Controllers.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

OB2538 OB2538 OB2538 PWM OB2538 OB2538 1 OB2538 PWM 2 OB2538 PWM 3 OB2538 PWM 4 OB2538 PWM OB2538 OB2538 OB2538 5 OB2538 OB2538 OB2538 OB2538 OB2538 PWM OB2538 6 OB2538 PWM OB2538 OB2538 OB2538 OB2538 7 OB2538 PWM OB2538 8 [ ... ]

OB2538 PDF Datasheet Download