New Electronics Roundtable: Embedded power

Their departure leaves a gap and the industry is having to support those who are now responsible for power supply design, but who may not be completely comfortable with the technology. A recent survey of New Electronics' readers found that 70% of engineers spend less than 20% of their time on power supply design and that a third have less time available than previously for this task. When asked about your knowledge, 71% could only say 'fair'. Patrick Le Fèvre, marketing and communication director for Ericsson Power Modules, said: "We've had to offer more support over the last 10 years because there are fewer pure power designers, except in larger companies." Alastair Boyd, UK managing director for Linear Technology, added: "It's becoming harder to support all the different companies, so we're developing web based tools: helping designers to help themselves." Carey Windeatt, sales and marketing project manager for TDK-Lambda UK, said: "There are companies with little or no in house knowledge – and it's those we're trying to help." Le Fèvre pointed out that, while more and more designers are struggling with power, time to market pressure is increasing. "This is now crucial," he claimed. Boyd added: "The quicker to market companies are with their products, the more money they make and penalty costs are becoming more common when companies don't deliver on time." Le Fèvre sees the decline in power knowledge as part of an industry transition from analogue to digital electronics. "Engineers are familiar with digital design, so they're a bit lost when it comes to power. They can deal with 1s and 0s – they're the 'iWhatever' generation and often wonder what an analogue function is." He says designers need to learn new skills quickly and implement them. "And we need to provide tools which are easy to use and to reuse." The problem, he believes, is that power supply design isn't a core activity for most. "They don't deal with power every day, so we need to remove complexity and provide support." But he says it's a two way street, particularly when it comes to dealing with a new generation of engineers. "They speak a different language, so whatever we do has to be easy to understand, easy to use and must plug into the digital chain." One solution, says Le Fèvre, is graphical tools. But the interface must be suitable. "It should be intuitive, open and able to take care of the whole board. The tool should also provide information from a range of suppliers." Ericsson believes the basis is the PMBus; an open power management protocol that supports communication with converters and other devices in a power system. "The PMBus is familiar to the 'iWhatever' community," Le Fèvre claimed. "It simplifies communication." But will the PMBus approach migrate to the industrial sector? "I'm not convinced," said Boyd. Windeatt's view? "PMBus isn't a standard and it doesn't guarantee a device will work in a system." Boyd sees pressure coming from greater use of fpgas. "Core voltages could be as low as 0.85V, ±3%," he noted, "with currents in excess of 20A. The supply has to be close to the fpga, it needs dc accuracy and it's not just about parasitics within the power supply; there are also board and layout issues." Le Fèvre added: "An fpga requires different supply voltages and these must be sequenced correctly. Voltages must be guaranteed so there is no damage to the fpga. Using a GUI, values such as voltage, margins, rise time and delay, can be set and validated. If a new sequence is required, it's only a matter of entering the new values." Boyd continued: "FPGAs are driving demands because of their technology. With lower voltages and more current; design isn't trivial. This is forcing suppliers to enter into dialogue with power supply companies, because they want to offer reference designs and recommended solutions for their next generation product." But reference designs aren't a complete solution; they are there to make an fpga work under most conditions and there remains the need to optimise. Windeatt picked up the knowledge theme. "We're often addressing those designers who claim power is 'not my job'. They're faced with a range of confusing solutions and their lack of expertise is compounded by greater complexity and limited design time." So Windeatt believes the route is 'solutions, not products'. "It's still a relatively new concept, but designers can see the advantage." Yet he sees obstacles. "Industry is conservative and risk averse," he claimed. TDK-Lambda wants to provide the key elements of a board level power solution. "Trusted products which make solutions to complex problems easier to implement," said Windeatt. "They are designed by experts, whose mission is to optimise the design without the need for additional components or tools." Even so, it's far from 'plug and play'. "Factors such as loop stability and parasitic inductance mean a product can become unstable, so designers can't 'cut and paste' to save time – even small changes can have large effects." This requires clarity from suppliers, said Windeatt. "We all need to provide clear information, so the device does what the datasheet says it will." Nevertheless, suppliers are striving to remove complexity. "We want to create as much of a 'black box' as we can," Windeatt continued. Boyd asked: "What is meant by standardisation? Is it commoditisation, where who can make it cheaper wins? If that's the case, it's not standardisation." Le Fèvre sees problems with a black box approach. "There are attempts to standardise and pressure from OEMs for commoditisation. But it can be hard to understand who is trying to standardise what and the market is too large and fragmented." Boyd also worries about knowledge. "Lack of expertise is a problem. It's a challenge to capture knowledge and to put it into products. Because Linear offers discrete components, we have power supply design tools where customers can put in a spec, select products, deal with compensation and so on. "But the sheer variety of applications – from driving an led upwards – means we need to offer hundreds of power supply components." Linear has packaged its power supply expertise in the form of the µModule. Boyd said: "We're taking our power supply expertise and putting it into a 15 x 15mm package. This is a complete power supply for digital engineers and one of fastest growing areas for Linear." Despite its crucial role in every product, power is often left to the last moment. Sometimes, it's a question of priorities; the fpga may well have to be developed before the power supply can be designed. Concluding, Boyd said: "Engineers leave power supply design to the last minute because they assume there's a solution." * For an extended version of this article, go to www.newelectronics.co.uk and enter 41007 in the search box. (box) The Embedded Power roundtable was sponsored by: Ericsson Linear Technology TDK-Lambda please use logos (end)