During device opening internal chips are enabled and configured. This results in consumption increases, specially when the 100 MHz clock (PLL) is started. The needed current increases from 100mA to 500mA. In case the USB can't provide enough current the voltage drops below the minimal required for the device to operate and communication fails.
In case you get “Device configuration failed (PLL 1)" or "Communication with the device failed.” error message:
The device needs