POWER ELECTRONICS SPECIAL: Expert panel

Tim Fryer: When asked what were the main reasons for selecting board level components, 97% of responders said device performance was a key issue compared to 90% in 2011. Bigger changes were noted in the importance of cost at 82% (72% in 2011) and availability at 88% (71%). Performance, cost and availability are clearly not taken for granted by designers, but what are suppliers doing about them? Reinhold Theurer: There is now a wealth of efficient power management products and system solutions that can be quickly integrated into a target design. As well as reducing the time and cost, choosing these technologies can often help engineers to address other key criteria, such as board space. Brandon Howell: The priority of performance versus cost tends to vary by end market. Most customers tend to weigh performance as the first priority, with cost following. Another concern is availability and most customers prefer to have a second source whenever possible, usually for fets, inductors and capacitors. A big differentiator is design support. The more, the better. Christian André: The power market is getting competitive, which leads to the question of cost and time to market. ROHM's answer to the market's evolvement is 'vertical integration'. We make everything from ingot to device, which allows us to be flexible and independent from external suppliers. TF: 30% of engineers said the time available for board level power design had decreased – a similar number to that in 2011. Is time for power design in particular dwindling constantly or is this just a trend across all aspects of design? BH:Generally speaking, power expertise at customers is in short supply and dwindling. The best suppliers alleviate this shortfall through integration and advanced controllers, with important capabilities such as auto-compensation, and inherently stable control loops. High levels of integration are important. Doug Bailey (pictured): We see a general trend across the whole industry towards a reduced time to market. Perhaps this is compounded when considering power supply design, since there are fewer specialist power supply designers. Power Integrations ics remove or simplify design tasks. For example, the high-voltage mosfet used in the LinkSwitch-II ic means that no primary clamp is required, which reduces component count and design complexity. We also provide design tools, such as PI Expert – an automated, GUI driven program that takes power supply specifications and generates a power conversion solution automatically. CA: The pressure to develop quicker and introduce ever sophisticated products to the market in a shorter timeframe can be seen across all segments. In the power management sector, it concerns a vital process, so these demands make power designs specially challenging. Suppliers have to be close to the industry, in order to learn about specific needs at the early stage and to offer the right products. RT: In the current design environment, engineers are increasingly required to do more with fewer resources, but are still expected to reduce time to market for new products. To help support their efforts, suppliers offer a broad array of design tools such as reference designs, simulation models and online design utilities. TF: 42% said their knowledge of board level power components and design techniques was 'fair, but needs brushing up', but a further 34% conceded it was 'not as good as it could be'. What are suppliers doing to address this? BH: Technical support through the entire design process is becoming a key differentiator. The more technical support available, the more comfortable customers are in taking on new technologies. Technical support tends to help reduce design risk and assure users they can succeed. The best suppliers are willing to provide as much support as possible; we are starting to become the customer's power design experts/advisers. CA: The introduction of new materials and process, such as silicon carbide, call for support and education. Our website has a support area for Power Management LSI, where designers can find an 'electronic laboratory' and use a 'design simulation tool' which helps them evaluating the right products. RT: Providing technical resources to help engineers keep up to date with the latest developments is an important part of being a technology leader. In addition to web based design tools, field training for our customers and distribution partners is also important and, by publishing technical papers and articles, we are providing engineers with many sources of information to stay on top of advancements in power electronics. TF: Three quarters of respondents do not use any form of thermal modelling, either using a standalone package or as a component of the design software, and yet it was identified as top of our 'key issues'. Is there a lack of understanding/appreciation? DB: Thermal modelling tools provide a decent approximation of what's going on, but designers who are looking for very high performance will need a more accurate method. So, sadly, although we invest in all the latest tools, we have never found a more reliable, faster or more cost effective means of really seeing what's going on – in the real world – than by building a supply and testing it. I suspect many design engineers will recognise this conundrum: while they would love to use new, advanced methods, they are simply not accurate enough – yet! RT: As many designers seek to design more functions into increasingly smaller physical spaces, thermal management becomes more important. Thermal constraints are key determinants for many design decisions, which can lead to a complex set of trade offs. The simulation software that is now available to engineers can help in making thermal design decisions. TF: 21% of people were outsourcing their board level power designs (see fig 1). Does breaking off this core part of the design and outsourcing it work? BH: In general, outsourcing such a critical portion of the overall system design never produces the same quality of results as doing it in house. Digital power and the PMBus standard have added additional system level functionality, such as supply/system health monitoring, real time power usage, extensive fault monitoring, and easy configurability. Users who can take advantage of these features will be best positioned to deliver robust systems. Outsourcing power design makes it harder to achieve this. DB: The 'make' or 'buy' decision is not straightforward. For example, increasing integration should reduce design complexity, meaning that it is better to 'make'. Yet increasing performance demands such as miniaturisation or high efficiency would skew the decision towards 'buy'. Simply, there is a spectrum of complexity/cost/volume conditions which will mean that, in some circumstances, outsourcing power supply design will work, in others it won't. CA: Power design involves specific skills, relying on external experts could be a solution to acquire the knowledge in shorter term. The Panel: Christian André, president, ROHM Semiconductor Europe, Doug Bailey, vp marketing, Power Integrations Reinhold Theurer, vp of European sales, International Rectifier Brandon Howell, field applications engineer, Intersil