This part is a kind of semiconductor called AP1534.

Function of this product has PWM CONTROL 2A STEP-DOWN CONVERTER.

Manufacturers : Diodes Incorporated

Image and pinout :

Some of the text within the PDF file :

AP1534 PWM CONTROL 2A STEP-DOWN CONVERTER Description Pin Assignments AP1534 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS. AP1534 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0 up to 99%. This converter also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. An enable function, an over current protect function and a short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced from 300KHz to 50KHz. Also, an internal compensation block is built in to minimize [ ... ]

AP1534 PDF Datasheet Download