Originally, DVDDIO was targeted to go up to 3.5V. During qualification, it was decided to limit DVDDIO to the limit specified in the datasheet: 1.7 to 1.9V. Maxim created a new reference design board to address this and followed the datasheet recommendations. The 3.3V of the evaluation board (SC2200 EV Kit) used for the Atmel chip is also used for the SPI interface. The new reference design does NOT include the Atmel chip and would require a separate board SC-USB-SPI2#. It was decided that it is fine to keep the DVDDIO at 3.3V for evaluation, but customers should limit it to 1.7V to 1.9V for their designs. It was decided to keep the current evaluation board for evaluation, but to recommend the new reference design boards for customer designs. For new designs, it is recommended to use the files from the reference design board and not the evaluation kit.