analog/digital ground loop: should analog supply be electrically isolated from digital?

correcting:
I'm designing a TMS320F28335 based control card but I have got a little confused whether analog power supply must be isolated from digital power supply. Section 3.5 of TI hardware guidelines (www.ti.com/.../spraas1b.pdf) states that it should be isolated, but tms320f2833x design reference (http://www.ti.com/tool/SPRC541) shows the application of ferrite beads to generate analog supply from digital. I'm concerned not only about A/D good operation, but also about ground loops that could arise if I use beads and capacitors to decouple analog supply.
I would like to hear from you.

Thanks everyone,
Fernando

Hi Fernando,

It is always better to have an isolated analog and digital supplies esp. when you've a converter functioning at higher powers.

Regards,
Gautam