The disclosure is directed to a memory device and a power reduction method of the same memory device. In an aspect, the disclosure is directed to a memory device which includes not limited to a plurality of memory banks, each having a power switch, a plurality of functional blocks for reading and writing to the plurality of memory banks and include a plurality of power switches as each functional block of the plurality of function blocks has a different power switch which turns on or turns off the functional block, a mode register circuit having a plurality of mode registers which determines whether one or more of the plurality of memory banks would maintain data storage or not, and a control logic circuit for either powering on or powering off each of the plurality of memory banks and each of the plurality of the functional blocks.