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This paper proposes a NAND controller system with a NAND channel number detector for 3D-integrated SSD. The control techniques of a program-voltage generator and an I/O frequency are proposed to enhance the SSD performance. This paper presents the solutions for the problems such as the rising time degradation and the increased power consumption caused by multi-channel parallel operation. The proposed NAND channel number detector automatically detects the number of accessed channels, that is, the number of NAND chips written at the same time. Based on the number of accessed channels, the intelligent program-voltage booster adaptively optimizes the switching clock. As a result, the proposed 3D-SSD realizes both the fastest write and the lowest energy consumption. The proposed 3D-SSD increases the write speed by 60% and decreases the energy consumption of the booster by 32%. Moreover, a dynamic I/O frequency control scheme is proposed for the future high speed I/O 3D-SSD. By selecting the adequate I/O frequencies based on the accessed number of channels, the summation of the SSD and the I/O power consumption is kept below 3.5 W even if 24 channels are operated in parallel.
Date of Publication: June 2012