US Patent 11182088 Operation method of a controller

A method for operating a controller which controls a memory device including a plurality of memory blocks operating in multi-level cell mode or a single level cell mode includes setting some of the plurality of memory blocks operating in the multi-level cell mode, to system memory blocks in response to a power-off request from a host, setting the system memory blocks to the single level cell mode, and controlling the memory device to store system data in the system memory blocks.