This part is a kind of semiconductor called AP3105.

Function of this product has High Voltage Green Mode PWM Controller.

Manufacturers : BCD

Image and pinout :

Some of the text within the PDF file :

Application Note 1062 High Voltage Green Mode PWM Controller AP3105 Prepared by Wu Qikun System Engineering Dept. 1. Introduction The AP3105 is a low start-up current, current mode PWM controller with green-mode power-saving operation. Different from AP3103, AP3105 PWM switching frequency at normal operation is fixed at 65kHz dithering with a narrow range. The difference between AP3103/AP3105 is shown in Table 1. The dithering of frequency will improve 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. A minimum 20kHz frequency switching is to avoid the audible noise as well as reducing the standby loss. A so-called VCC Maintain Mode is applied under light load to realize a stable [ ... ]

AP3105 PDF Datasheet Download