You should never apply a voltage potential that is greater than the respective supply voltage for any terminal that is not fail-safe.
USB0_VBUS and USB1_VBUS are the only fail-safe terminals on AM335x. Therefore, you must not apply any potential to the analog inputs when the device is powered off.
This requirement should be applied for all conditions, power-off, power-up, power-on, and power-down.
Regards,
Paul