I/O voltage levels
Added by Bhima Shankar about 12 hours ago
In the data sheet of MITY-SOM_AM57F SOM board page 4, it is mentioned that the AM57XX MFIOs are operating at 1.8V level except mmc1 pins. We have an I2C connections that goes to AM57XX processor, we need the voltage levels of the I2C pins to be 3.3V. Can we do it just by pulling up the I2C pins to 3.3V or should we need to use level shifters or should we do any changes in the SOM board?
Please help us with this issue.
Replies (3)
RE: I/O voltage levels - Added by Michael Williamson about 11 hours ago
Hello,
You should use level shifters to shift up to 3.3V. Do not pull the I2C pins directly to 3.3V or modify the SOM.
Our Dev Kit schematic uses TCA9803DGKR, but there are several shifters avialable that should work.
Which I2C pair are you using?
-Mike
RE: I/O voltage levels - Added by Bhima Shankar about 11 hours ago
Hello Mike,
Thank you for your swift and helpful response.
We are planning to use I2C3, I2C4, and I2C5 interfaces of AM57XX in our design.
Kindly correct us if we are mistaken — as we understand from the documentation, all I/O pins on the SOM, except those associated with MMC1, operate at 1.8V logic levels. Therefore, if we intend to interface with devices that require a different voltage level (e.g., 3.3V), the use of level shifters would be necessary.
Please confirm if our understanding is correct or let us know if there are any exceptions or recommended approaches.
Thank you once again for your support.
Best Regards
Shankar
RE: I/O voltage levels - Added by Michael Williamson about 10 hours ago
The SOM ties the following AM57x voltage IO domains to 1.8V. You will need to use level shifters on your board to get to +3.3V IO interfaces.
VDDSHV1
VDDSHV2
VDDSHV3
VDDSHV4
VDDSHV6
VDDSHV7
VDDSHV9
VDDSHV10
VDDSHV11
VDDSHV8, which corresponds to the MMC1 interface, is tied to a separate supply that is nominally +3.3V at startup but can be switch to +1.8V during runtime.
With regards,
Mike
