This part is a kind of semiconductor called AP3503.

Function of this product has 3A Synchronous DC-DC Buck Converter.

Manufacturers : BCD

Image and pinout :

Some of the text within the PDF file :

Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503 General Description The AP3503 is a 340kHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 3A load with high efficiency, excellent line and load regulation. The device integrates N-channel power MOSFET switches with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. The AP3503 employs complete protection to ensure system security. Including output Over Voltage Protection, input Under Voltage LockOut, programmable soft-start, Over Temperature Protection to safeguard the circuit. This IC is available in PSOP-8 package. Features • Input Voltage Range: 4.5V to 18V • Fixed 340kHz Frequency • High Efficiency: up to 9 [ ... ]

AP3503 PDF Datasheet Download