Firmware Atmega16u2, MEGA2560

Hi guys, I have one new application and I need to burn a new Chip "Atmel". I have bought it virgin, in digikey. But the I have not get that my computer read my new Chip as "Arduino Mega 2560"

DO you know what is the correct file .hex (firmware) to program one Atmega16u2, inside MEGA2560??? I have been testing different files without successful. All is inside these chapters:

C:\Program Files (x86)\Arduino\hardware\arduino\avr\firmwares\atmegaxxu2

oder: C:\Program Files (x86)\Arduino\hardware\arduino\avr\firmwares\atmegaxxu2\arduino-usbserial

otherwise, I have been testing with another .hex but, at the moment I have only get one "unknown file" in the "Device manager".