Hi everybody,

I'm working in laptop repairing and i see in schematic there is two MOSFET connected like in the photo below , my question is why to use two MOSFET instead of one.
Thanks in advance.

 

Difficult to tell with so little of the diagram but I would guess that the top one is switching power through the inductor and the bottom one is a synchronous rectifier.

 

One is high (drain connected to upper rail, source not connected to ground) and one is low (source connected to ground). They probably would not ever be turned "on" at the same time, since that would short the 5V rail to ground.