5261 - ECP5/ECP5-5G: Does DDR3 SDRAM controller IP support DDR3L?
Yes, the DDR3 SDRAM controller IP support DDR3L 1.5V operation. It also supports 1.35V operation, but SSTL15 should be changed to SSTL135. Refer to the ECP5 and ECP5-5G sysIO Usage Guide (FPGA-TN-02032).