Download the MT8VDDT1664A datasheet PDF.
This datasheet also covers the MT8VDDT6464A variant, as both devices belong to the same (mt8vddtxx64a) 184-pin ddr sdram dimms family and are provided as variant models within a single manufacturer datasheet.
Note: The manufacturer provides a single datasheet file (MT8VDDT6464A_MicronSemiconductorProducts.pdf) that lists specifications for multiple related part numbers.