Microcontroller Peripheral Voltage ranges and Drive strength

[Freshman]

I have this Microcontroller, https://ww1.microchip.com/downloads/aemDocuments/documents/MCU32/ProductDocuments/DataSheets/SAM-D5x-E5x-Family-Data-Sheet-DS60001507.pdf, where they mention the acceptable voltage levels in between 1.7V to 3.63V.

But under USB section, page 1884, they mention for USB, we need 3.3V.

But for other peripherals like, I2C, ADC, SPI, I didn't see such mention of required voltages.

So my questions:

1. If I give 1.8V as Vcc to the MCU, I can work with other peripheral perfectly fine except USB? Or what peripherals will be affected or the ones I need to take care if I use 1.8V as Vcc?

2. While researching more on this, I found on page 1846 that , "Note: Note: The PA24 and PA25 pads do not have Drive Strength capability.". These are USB datalines. What does it mean that they don't have drive strength capability?

[Leuams]

On most of the datasheet I have read the voltage range impacts the maximum clock frequency that the MCU can run at. The USB peripheral most likely needs a clock frequency that the lower voltages can't reliably run.

[newbrain]

The peripherals internal to the MCU will still work in the recommended range (check for clock speed limitations at lower voltages), but, of course, when you connect something to the I2C or the SPI the levels must be compatible.

For 1.8 V, this is not usually the case if the external peripheral is powered by 3.3 V.

Consider also that the maximum operating conditions state that Vpin must be at most Vdd+0.6 V.
This means that a MISO input for SPI or SCL/SDA with a 3.3 V pull up for I2C would be exceeding the maximum allowed input voltage.

As for the second question: the drive strength of (most) IO pins can be set by SW, USB lines lack this possibility.