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Myth busters: Are digital or analog power modules cheaper?

-August 21, 2013

Digital power is arguably one of the most important technology evolutions to emerge in recent years.  It provides real-time, precisely optimized power conversion utilizing advanced algorithms, greater design flexibility, and the ability to use power saving features to cut overall consumption in the system.

 

Thanks to its advantages, digital power is becoming widely adopted for telecom and networking systems, which draw lots of power and features sophisticated/ complicated power management structures. In fact, a study released by IHS titled The World Market for Digital Power sees the market growing from $2.7 billion in 2012 to $12.4 billion in 2017 driven largely by the datacom and telecom markets.

 

But an interesting misconception was uncovered in the survey of manufacturers used to construct the IHS study.  A total of 27% of manufacturers and designers indicated that cost is still a major barrier in adopting digital power.  IHS states that "this highlights a lack of knowledge…regarding the overall cost savings that digital solutions can provide."

 

Here at CUI, we make both digital and analog power modules; so will be pretty much neutral on this topic. And we strongly believe that when the overall design costs are taken into consideration, digital power has the potential to cut these costs significantly for many applications, thus making the perception that “digital power is expensive” nothing more than a myth.

 

But as with many things in life, it is all in the definition. If you are looking at the straight-up module cost an analog vs. a digital version, then yes, the analog module will likely be a cheaper solution. However, if you look at the total cost, or the “value” of the digital module versus an analog solution, then digital will in fact be “cheaper”.  Here we look at some of the hidden design costs to help bust this myth.

 

 

Digital power reduces board spins – Each board spin in the design process can cost on the order of $40,000 (and significantly over). Each spin can also add several months to a project. Digital power allows changes to be made in the software, rather than via board level component changes – cutting this time and expense from a project.

 

Digital power cuts time to market – Delays cost money and digital power not only leads to a reduction in board spins, it also eliminates the need to undertake labor-intensive, time-consuming aspects of analog power design, including manual loop compensation and the design of margins to account for component aging, manufacturing variations, and temperature.  Additionally, on the fly modification to system parameters can be undertaken via a GUI during the development phase, cutting months off a system’s development.

 

Digital power minimizes total solution cost – Analog POLs require up to 10x the external capacitance. This therefore requires additional external components, adding to both the total solution cost and the overall board space required in the application.

 

Digital power incorporates power management - In today’s systems it isn’t just about converting one voltage to another voltage, you must also worry about sequencing, tracking, fault management, etc. With an analog module external ICs and circuitry will be required to perform these tasks, increasing the overall cost and board space. In a digital module, these functions are all preformed internally without the need for additional components or circuitry.

 

Digital power enables “cut and paste” designs– Implementing analog comes with a second, hidden limitation… the fixed circuit based on the previous board specifications (usually) cannot be implemented “as is” for new designs. While the core components may be reused, the analog solution itself must be modified as the new design will have different timing needs, sequencing and faults. And all will require a new layout that incorporates these modifications. Conversely, the dynamic nature of digital designs can be easily “cut and pasted” from one board to the next. Changes will still be needed, but these can be quickly implemented through the GUI.

Digital power does not have to be an “all or none” proposition. When considering today’s most sensitive and difficult to support sockets (such as an FPGA), digital has incredible value and should be the first area you look to implement this technology. All of the values outlined above can be considered for a complete board or a single socket.  An error in one of these complex sockets can cause a redesign of the entire board in an analog scenario. Moving those particular sockets to a digital solution will allow greater flexibility to trouble shoot and make modifications via software, thus mitigating some of the project risk.

Summary

For some, analog systems will still be the right option. But the myth that ‘digital is expensive’ is just that, a myth. The system’s complete design costs need to be taken into account before deciding on an analog or digital system.

At the end of the day, it comes down to the perception of cost. Are you only looking at the BOM cost of the power module, or are you taking into account the additional factors such as external component count, design costs, and flexibility for future product platforms?  We want you to base that decision on all the available information. And once you have, we have the digital power modules as well as the ac-dc power supplies and analog dc-dc converters to support your designs.

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