Some analysts have said the deal was most likely done to keep Fairchild out of the hands of a competitor, particularly China's Tsinghua Unigroup, which has ambitions of becoming the world's No. 3 chipmaker.
Fairchild did not release China Resource's name on Tuesday as the company that made the unsolicited bid.
A chip industry pioneer, Fairchild has been struggling to boost revenue growth due to slowing demand.
German chipmaker Infineon Technologies was also rumored to be after Fairchild.
Fairchild said its board would consider the unsolicited bid but still supports the agreement with ON Semiconductor.
— CNBC's David Faber contributed to this report.