High voltage tolerant IO pins


We are developing our own carrier for the Jetson Nano.
I see in the device tree that some pins can have High Voltage IO enabled.
I’m wondering what this does and how it is implemented. For example the I2C lines have this enabled and are pulled up to the 3V3 line.

Can somebody please explain me what this actually is and how to use it?

  • does it only mean 3V3 input tolerant?
  • What happens when I configure the pin as an output?


They are 3v3 input tolerant, and will output 1.8v as the power supply does.