The title of this blog harkens back to the 1970s book, Zen and the Art of Motorcycle Maintenance, which is the best-selling philosophy book ever in the USA. I have chosen to borrow from it because in PDS design there is often a misunderstanding of the concept of quality and the conflict that arises when there is an absence of it. And, there exists something like a PDS Karma—every engineering effort undertaken in the PDS design process has a consequence in current or future hardware development efforts.
The design of power delivery systems has elements similar to other features within hardware design and, as a result:
This blog will address the foregoing bullets with particular attention paid to the last one.
Why PDS Design Is Such a Big Deal
The number and character of factors that have to be addressed during PDS design include:
Addressing the foregoing is a big challenge in and of itself but when the particulars of today’s technologies are considered it’s easy to see why PDS design takes so much time and effort.
The Wrinkles Presented by Today’s Technologies
The elements of current technologies that significantly impact PDS design are due to but not limited to the following:
Who Is Being Most Impacted by PDS Design?
A few years back, complex PDS design was limited to high-end, complex power delivery systems and the engineers involved in designing them became aware of the challenges associated with the PDS design process.
The people who are being caught a bit off-guard now are those who have been designing consumer electronics. Prior to current designs, PDS design in consumer electronics involved connecting the dots. Now that complex PDS designs are in consumer-level electronics, there are product developers who are being taken by surprise.
And, the complex PDS design process is not limited to a handful of products. About every product you can name has taken advantage of the huge ICs with millions of transistors to do more complex operations. The reality is that everybody wants a faster computer; everyone wants a video game that runs quicker, and everyone wants their Internet router to go faster.
Of the foregoing, the biggest operations within any device are linked to graphics processing. For instance, the technology that comes into play when a mobile phone is rotated from vertical to horizontal such that the screen remains in alignment requires the technology capability that we used to refer to as a supercomputer. There are so many features in a smartphone—several radios, one or more cameras, the screen, the processors inside, and the memory all of which consume power. It becomes a real challenge to manage all of the various power zones. It’s important to remember that for every power rail in a device there is a PDS and it is not uncommon to have 15-20+ PDSs in a smartphone.
Where Does PDS Come Into the Overall Product Development Process?
The good news is that routing a design has become easier because of differential signaling but it means that the PDS should be designed first. Actually, you can’t design the PCB stackup until you have designed the PDS. And the following factors need to be taken into account:
Common Mistakes Made When Designing a PDS
Given the foregoing, there are a lot of places where mistakes can be made in creating a PDS design but below are some of the most common ones:
Because it’s not possible to do in-circuit testing, it’s crucial that the PDS is always guaranteed to work and is always stable. If the PDS is screwed up at the design phase, there are no band-aid fixes. The only solution is to throw away the PCB and all the chips and start the design process from square one. It’s the Tsunami of a failed design—the board is lost, the chips are lost, the product window can be missed, and the competitive edge can be lost. This is why the traditional approach of respinning a design two or three times is not a valid product development approach (nor has it ever been).
What Are The Critical Must Haves?
Given the foregoing, there are some must haves to ensure that a working, reliable PDS is created. They include:
Want to achieve PDS Nirvana?
Given the foregoing, there are lots of pieces/parts that go into successfully designing a working PDS. There have been numerous articles and books that have addressed PDS either as a stand-alone topic or as part of the overall system design process. For those who are new to the PDS design process or are struggling with an existing PDS design, there is a one-day, on-line course now being offered through Endeavor Business Media that is accessible through: Power Delivery System Design – Engineering Academy (designengineeracademy.com). The course is taught by Speeding Edge President, Lee Ritchey. More than 12,000 engineers world-wide have participated in his on-line and in-person training classes and Lee bases all of his training on the real-world hardware that he has designed for more than five decades.