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PI‐A165: Towards Zero Standby Power – designers get smart to meet new energy regulations Towards Zero Standby Power – Designers Get Smart to Meet New Energy Regulations By Andrew Smith, Product Marketing Manager, Power Integrations In order to meet ever‐more‐stringent energy consumption limits, designers of an increasingly wide range of products have to change their design practices and spend more time researching solutions and new technologies. This pattern is a worldwide trend with tough standards being driven out of China, Europe and the USA. Additionally, the global nature of business in 2012 means that no region stands in isolation and many products must be designed to meet all international regulations. Initially, regulators targeted external power supplies because they are easy to separate from the system that they supply. Now, however, a much wider portfolio of products is being considered including computers/displays, imaging equipment, laundry driers, vacuum cleaners and even domestic coffee machines. And in Europe, there is already a long list of other products that will be investigated, analysed and eventually be subject to mandatory efficiency performance standards. When agreeing on minimum efficiency performance, the energy regulators tend to map the efficiency performance of a cross‐section of the market and base performance targets on what is being achieved by a percentage of the best‐performing products that are currently available. One particular issue that has been bothering regulators worldwide is the amount of energy that products consume whilst in standby mode, and many of the emerging efficiency formulae are split into two parts examining elements for standby and no‐load power, as well as for full operational mode consumption. The target is, of course, ‘zero no‐load’, where a product consumes absolutely no power when idle. Currently there is no international standard that requires zero standby power usage for any products; however, there is a clear move in this direction, and a genuine commitment to drive down energy consumption within the electronics industry and certainly among the major OEMs. The IEC has even defined “zero power” as less than 0.005 W (IEC62301 Clause 4.5 rounds standby power use below 5 mW to zero). The good news is that reducing standby power is really a matter of careful design and appropriate power IC choice, which costs nothing more than the will to change and an innovative attitude. Whereas system designers may be limited in what they are able to achieve, IC designers have much more flexibility to innovate new solutions. A case in point are two products introduced by Power Integrations last year which are completely new and different in concept for us and industry as a whole, yet both contribute to making ‘zero no load’ a reality. CAPZero is an automatic X capacitor discharge IC. When an AC voltage is applied, CAPZero blocks current flow in the X capacitor safety discharge resistors, reducing the power loss to less than 5 mW at 230 VAC. When AC PI‐A165: Towards Zero Standby Power – designers get smart to meet new energy regulations voltage is disconnected, CAPZero automatically discharges the X capacitor by connecting the bleed resistors in parallel. This operation allows total flexibility in the choice of the X capacitor to optimize differential mode EMI filtering and reduce inductor costs, with no effect on power consumption. The simplicity and ruggedness of the two terminal CAPZero chips makes it an ideal choice in systems designed to meet EuP Lot 6 and safety requirements. SENZero is a compact (SO‐8) low cost solution to eliminate losses in resistive signal paths connected between high‐voltage rails and switching power supply controller by switching them out of circuit during no‐load operation. Examples include feed‐forward or feedback signal paths connected to boost controllers in power factor corrected systems and feed‐forward signal paths in two switch forward / LLC / half and full bridge converters. These are just two examples of products that solve a problem in very different ways to traditional methods, eliminating the wasted energy that is normally associated with such older techniques.