I am trying to lay out a PCB for a SEPIC switching regulator. However, I cannot be sure how to layout the ground tracks. My area and budget are limited and my components are big. A picture says more than my words, so here are the schematic, my questions and some more details:
I only included some of the components for the sake of simplicity, if the whole schematic needed, I can upload.
Grounds of CU2, U2 and U1 are tied together (may be daisy chained), then gathered in one point which is "AGND".
Grounds of C1 (which supplies the additional current to the push-pull driver since 78L12 can only supply 100mA), Q2 and Q3 are star tied together at one point that is "PGND".
Then, PGND and AGND are star tied to the ground point of C6, which I've chosen to be the reference point.
- If my star network is connected wrong or can be problematic, how should I organize it?
- Is the ground side of C6 a good place for the reference point for the star ground network?
- Will daisy-chaining AGND nodes lead to problems?
- Should I star-connect 12V rails, if so, how? (U1 has a 100nF bypass cap which is not shown here)
If it will help, here is my current board layout for the mentioned part: