Hi Srinivasarao,
Using the UCD9222 and the UCD7242 as you've described is an approved method of generating the smart reflex power supply needed for the C6678. You may also want to look at the UCD74120 as an alternate to the UCD7274. This is a 20A power stage component. You can find an example of a design using that component on the K2X EVM found at http://www.advantech.com/Support/TI-EVM/EVMK2HX_sd3.aspx.
Regards, Bill