CY4618 RDK has obsoleted.
For a replacement, one can use :
1. http://www.cypress.com/?mpn=CY7C68023-56LTXC : This is a fixed function part and won't work with all NANDs.
2. http://www.cypress.com/?mpn=CY7C68033-56LTXC is the flexible drop-in replacement version of it (has a firmware and can be modified to work with SLC NANDs with 1-bit ECC requirement).
All NAND controllers come with a compatibility list.
One should be looking at http://www.cypress.com/?rID=14320 for the firmware and the current compatibility list.If able to procure the NANDs in the compatibility list then you can design straight away else the firmware has to be modified.
Also link: http://www.cypress.com/?id=214&source=header can be referred for our westbridge series of products. Antioch and Astoria of this series are capable of supporting SLC NANDs upto 4bit ECC.This doesn't have a RDK specific for NAND Thumb Drive like CY4618.