This part is a kind of semiconductor called LTC4412.

Function of this product has Low Loss PowerPath Controller.

Manufacturers : Linear Technology

Image and pinout :

Some of the text within the PDF file :

Features nn Very Low Loss Replacement for Power Supply OR’ing Diodes nn Minimal External Components nn Automatic Switching Between DC Sources nn Simplifies Load Sharing with Multiple Batteries nn Low Quiescent Current: 11µA nn 3V to 28V AC/DC Adapter Voltage Range nn 2.5V to 28V Battery Voltage Range nn Reverse Battery Protection nn Drives Almost Any Size MOSFET for Wide Range of Current Requirements nn MOSFET Gate Protection Clamp nn Manual Control Input nn Low Profile (1mm) ThinSOT™ Package Applications nn Cellular Phones nn Notebook and Handheld Computers nn Digital Cameras nn USB-Powered Peripherals nn Uninterruptible Power Supplies nn Logic Controlled Power Switch L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PowerPath and ThinSOT are tradem [ ... ]

LTC4412 PDF Datasheet Download