Mity CPU Platforms » MitySOM-5CSX Altera Cyclone V

Stephen,

Thanks for reaching out to us about this question.

Please note that making any modification to the carrier board, such as this, will void any warranty for both the carrier board and any module used in that board.

Unfortunately the only way to easily change the IO bank voltages to support 3.0V/3.3V is to do as you described, change the output voltage of the U601 component from 2.5V to your desired voltage. This change is not expected to cause any negative impact however you will NEED to ensure the following:

• Your FPGA project must be rebuilt to support the new voltage levels for the affected pins.
• Your SD card/boot media must be updated with pre-loader and UBoot as well based upon the new FPGA image.
• All Bank 3B, 4A, 8A and 3A5A5B (for expanded IO modules) IO pins are affected
• Thus all HSMC pins will be affected by the change to U601

For the specific case of setting U601 to output 3.3V you would need to change the combination of R603 (ships as 12.1K) and R613 (ships as 12.1K) to total ~36.0K ohms on the development board.

• Remove either R603 or R613 and replace ONE of them with a ~23.7K ohm 1% resistor
• Please note that these are 0402 sized SMD resistors
• The value change for R603 or R613 was determined based upon leaving R616 as the original 11.5K value

Please reference the LT3502IDC#TRMPBF datasheet (http://cds.linear.com/docs/en/datasheet/3502fd.pdf), page 21, for their "typical application" resistor values and page 10 for the FB resistor calculation.

Please note that we have operated the development board at voltages other than the 3.3V discussed above and the standard 2.5V (i.e .3,0V and 1.8V). Please follow the LT3502 datasheet calculations closely if utilizing other voltage levels.

Thank you,

Alex

Thank you Alex, that's exactly what I wanted to know. I understand your point about the warranty, and proceeding carefully.

Best,

Steve