STM32U083MCT6TR, How should VDDUSB be handled when USB is not used and VDD = 1.8 V?

[Tal]

I’m designing a board using the STM32U083MCT6TR, and my system supply voltage is VDD = 1.8 V.
The design does not use USB at all.

The datasheet specifies that VDDUSB normally requires 3.0–3.6 V for USB operation, but it’s not fully clear what the correct connection is when USB functionality is not needed.

My question:
What is the recommended way to handle the VDDUSB pin when USB is unused and the MCU is powered at 1.8 V?

Should VDDUSB be tied to VDD (1.8 V)?

Should it be left unconnected?

Or is another configuration required?

If anyone has experience with the STM32U0 series or clarification from ST, I’d appreciate the guidance.

Thanks,

-Tal

[Gyessine]

Hello @Tal 
Based on AN6020 and AN4879, the usual recommendation is to connect VDDUSB to your main supply rail (VDD = 1.8 V).Do not leave VDDUSB floating .Also its recommended to local decoupling capacitor to ground, just like any other supply pin

BR
Gyessine