Eval-adau1467Z selfboot without USB connected

Hi there, 

I recently upgraded our evaluation board to the EVAL-ADAU1467Z, everything is going well, except I'm a bit confused by the self-boot operation.  I followed the instructions in the user manual and the self-boot appears to work, EXCEPT when the USBi is disconnected.  I thought the whole point was so you could have the unit disconnected from the programming PC?  Is there a way to overcome this?

Kind regards,