I talk with a lot of customers about their designs and what’s needed to get their products out the door and for the most part, they have many of the same challenges across all industries. One of the new areas that has been challenging digital designers the most has been in power. Not necessarily designing power supply circuits, but actually looking at power delivery on the PCB (i.e. power planes, area fills, capacitors).
So why is it a challenge suddenly? There are a variety of reasons that I could list, but here are a few of the main reasons:
1. Low voltage cores and I/O in ICs
2. Low power initiatives in IC design
3. Cheaper board costs (component and layer count)
Ultimately, we’re talking about what lies at the core of most engineering work – trading off cost vs. performance (including reliability). It’s a tough trade-off sometimes and without the proper tools, it’s hard to know what you can trade-off against. How do you know if you remove a power layer and go will positive planes with area fills that you are going to be providing enough copper? How do you decide if you burying power planes in the middle of the board vs. using the outer, what the better solution is? How do you select which capacitors you put on the board and where? Most designers don’t have the real estate to put them down as many as the IC manufacturer recommends, much less exactly the way they recommend it.
All of these can be tough answers to come-by but you can build some intuition about good design practices with the right set of tools as well as validate the design intent. My next few posts, I’ll look into this subject a bit further and discuss how these trends are impacting board design.