Based on the partial number and the package type (QFN20), a quick search of Google reveals Richtek RT6575A as a possible candidate. This is a "Dual-Channel Synchronous DC-DC Step-Down Controller". This makes sense from your description of its surrounding components.
This part has
3G= as its product code, with the remaining digits as a date code:
The part is in a 3mm x 3mm 20-pin QFN package - you would need to confirm with dimensions, but that looks about correct.
There is no much context in the image of the surrounding circuit, but the pinout is given in the datasheet. This can be compared to the circuit to see if it reasonably matches:
From this we can see that the four gate control pins (UGATEx/LGATEx) go to nice wide traces on the PCB which would make sense for controlling MOSFET gates. The output pins (PHASEx) also both go to nice thick traces which makes sense too. Further, the two bootstrap pins (BOOTx) both go to a resistor which is expected from the application circuit in the datasheet. There isn't any other context in the image to work on.