This part is a kind of semiconductor called AP8263.

Function of this product has PWM CONTROLLER.

Manufacturers : AiT Semiconductor

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Some of the text within the PDF file :

AiT Semiconductor Inc. www.ait-ic.com AP8263 PWM CONTROLLER GREEN MODE DESCRIPTION FEATURES The AP8263 includes all necessary function to build  Proprietary Frequency Jitter for EMI an easy and cost effective solution for low power  PFM Mode Control supplies to meet the international power conservation  Audio Noise Free requirements. AP8263 offers complete protection  Internal Slope Compensation coverage with automatic self-recovery feature  Owning soft start-up function including Cycle-by-Cycle current limiting (OCP), over  Good Protection Coverage With Auto Self- voltage protection (OVP), over temperature Recovery protection (OTP), soft-start and Burst mode  Available in SOT-26 Package operation. Excellent EMI performance is achieved with frequency modu [ ... ]

AP8263 PDF Datasheet Download