I'm laying out my PCB for the first prototype of my project. The board is relatively simple as it only consists of two CPLDs (Altera 240Z Max V) and a AT Mega 128L. I am now thinking of laying out the power section but am wondering if I should just power it from an external supply. The supply meets my requirements (3.3V and 1.8V rails) and has enough juice to run the board (2A @ 3.3V and 1A @ 1.8V).
I would really prefer this approach but am wondering if this is a good idea. It keeps the simplicity as it means I don't have to test and pick voltage regulators at this stage. The power requirements may even change in the future depending on my CPLDs. So my questions are:
Are there any drawbacks I should be aware of of this approach? Should the power section be always close to the relavent chips?
Based on the advice from my previous question, I feel I have sufficient decoupling now (0.01uF and 1uF caps on every power/gnd pair with very short loops). But should I include a large capacitor (say, 470uF) and apply power straight to that?