Myth busters: which is cheaper to implement, digital or analog power?

Digital power is arguably one of the most important technology evolutions to emerge in recent years. It enables systems to be precisely optimized, and for this to be done on the fly… taking into account many factors and, therefore cut overall power drawn by the system.

It has been widely adopted for telecom and networking systems, which draw lots of power. But, about 18 months ago, the technology was in danger of becoming niche, and seen as something that was too difficult to implement. The market responded, and products such as CUI’s NSM2P allowed system designers to implement digital power without the digital bus.

The next block in its uptake, however, doesn’t come from a technical issue but from a myth. That myth is: “digital power is expensive”.  However, when the overall design costs are taken into consideration, adopting digital power cuts the design costs significantly. Let’s look at some of the hidden design costs to bust this myth.

Module costs:

Lets look first at the initial figures and then again in more detail. A digital point of load module may have a listed dollar value that compares with a similar analog module, and at first glance choosing analog and undertaking procedures such as manual loop compensation will appear to save you money. But as with many things in life, this isn’t the entire story and several aspects must also be taken into consideration.

The key ones, in no particular order, are:

1) Digital power reduces board spins – Each board spin can cost in the order of $40,000 (and over), and adds several months to a project. Digital power allows changes to be made in the software, rather than via board-level component changes.

2) 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 manual loop compensation; on-the-fly modification to system parameters can be undertaken via a GUI, cutting months off a system’s development.

3) Digital power minimizes total solution cost – Analog POLs require up to 10x the external capacitance, requiring additional external components that add to both the total solution cost and the overall board space.

4) Digital power enables design reuse – 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. 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.

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. 

CUI