Memory device for selectively operating multiple memory groups in different speeds and memory system including the same

Abstract

A memory system includes a plurality of memory devices and a controller. Each of the memory devices includes a memory cell array, a sense amplifier for amplifying data stored in the memory cell array, a first memory cell sub-array included in the memory cell array directly coupled to the sense amplifier, a switch coupled to the first memory cell sub-array, and a second memory cell sub-array included in the memory cell array coupled to the sense amplifier through the first memory cell sub-array and the switch. When the switch is enabled, the memory device operates as a normal mode, and when the switch is disabled, the memory device operates as a fast mode faster than the normal mode. The controller dynamically sets a mode of each of the memory devices based on requests externally provided, by controlling the switch of each of the memory devices.