TMS320F28033: F28033 ground reference design

Sammi,

We'd recommend that you split the analog and digital grounds on this device but this isn't a hard requirement; good layout with a combined ground plane will likely give much better performance than bad layout, but with split planes.

One key to splitting the planes is to ensure that analog signals are routed over the analog plane/in the analog section and digital signals likewise are referenced to the digital planes and stay in the digital section. This will maximize performance by physically separating the two types of signals and should ensure that there is minimal voltage difference between the planes. 

We'd recommend that you join the analog and digital ground planes with a 0-ohm resistor right under the center of the chip. In the case a signal has a return path through both planes (this should be mostly avoided by good layout - no signal should be crossing the plane boundaries) the return current will have a path to flow through this common point. 

Regards,
PEter