I have a question regarding VDDUSB connection in STM32L452 MCU. Should it be applied all the time, or only when the USB cable is being connected? I was wondering either it is possible to apply it from the USB cable (with 5 V to 3.3 V conversion) because the device normally runs on battery and I dont want to power the USB module for the time of no USB connection if that is possible. If such solution would be considered, should one reinitialize the USB module in software each time USB is connected? In F4 device there was a dedicated pin for notifying the device that USB was connected. In STM32L4 there are only D+/D- lines available.
I would appreciate all help regarding this issue.