Hi Dalin,
The DM3730 processor supports 1 x16 LPDDR device is used for 16 bit LPDDR memory system or 1x32 or 2x16 LPDDR devices are used for a 32-bit LPDDR memory system.
For more details you can look at the Table 6-13. and the notes below in the DM3730 processor data sheet at the link:
http://www.ti.com/lit/ds/symlink/dm3730.pdf
BR
Tsvetolin Shulev