Hi.Originally posted in cdnusers.org by Malmir
Out of that info alone. Sorry but no.
Imagine You have a PC motherboard. Here You have the huge Power connetor with 3V3, 5V and 12V. The 1V8 i created near the cpu by a dc-dc converter (or as i call it a local PS ). But this board can be everything from 4 to N layers.
The board i'm at right now also is supplied by 12V and have 12 layers. But that is due to some DDR2 and some high pinnumbered BGA's with several diff pairs. If Yours is a power supply "only" 4 layers could be enought (read could, not is).
A thumbrule is having a bga where only 2 cline can go between pads or via's, You need a routing layer for each second ring of pad minus 2. EG having a bga of 10 * 10 pin gives 3 inner rings and thats demands 2 routing layers, and top + bottom + power/ground layers.
Sorry my explanation, but i could not find an easier way :-).