STM32U0 1.8V and USB 3.3V

[Decebalus]

Hello! I am working with a STM32U073 on 1.8V and I want to use the USB feature. Indeed, the datasheet tells us that USB needs a separate power supply around 3V (4.1 Power supplies), but every time when I apply this voltage on VDDUSB pin, it goes to the VDD pins too. And vice versa, if I supply only the VDD pins with 1.8V, same voltage is on VDDUSB, without traces between them. I set / cleared according to datasheet the PVM1, PVMO1 and USV bits (4.2.3 Peripheral Voltage Monitoring (PVM)). It can be something internal? I checked the PCB and traces and is nothing wrong. 

[TDK]

Custom board?

Take a continuity measurement when the board is off between VDD and VDDUSB. It should be very high impedance.

[Decebalus]

Yes, custom board. I did the tests before writing here, and it is a short. I remove the uC to
check the PCB and the traces are not shorted. I did a continuity test directly on the pins
(VDDUSB and VDD pads of the uC) and they are connected. I use a STM32U073KCU6 with UFQFPN32 footprint and in the datasheet (pinout) says that VDDUSB can be independent, but maybe the datasheet needs an update like STM32U535 WLCSP56 footprint: 21-Dec-2023 VDDUSB corrected to VDD.

[Decebalus]

I think I found the problem. In the pinout figure, VDDUSB is present, but in the table below says that UFQFPN32 package does not have a VDDUSB pin and probably is internally connected to VDD and so if I want to use USB with this STM32 I must supply a voltage above 3.0V. Correct me if I am wrong.

[Viktor POHORELY]

I confirm there is no dedicated VDDUSB on QFN32 package. Request for update of the drawing in DS has been already created, will be done with next planned revision of the document. Pinout table is correct.

Thank you to report this point and sorry for the difficulties.