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ANALOG & MIXED SIGNAL Fig. 1: A bank of KEMET multi-capacitor X7R stacks having a combined capacitance of 6000 μF at 25V rating. name a few. Ingenious circuit design engineers often adapt “off the shelf” components to satisfy special requirements, but they must usually accept some compromises when using commercially available parts to get the desired performance in leadingedge new product designs. For example, two components in series may be used to achieve the desired voltage capability because a single component with the desired capability is not available. A bulky, expensive ‘bank’ of components may be used in circuit designs where high ripple currents are present, because suitable components with high current capability do not exist. Many high-current and high-voltage circuits, particularly those that incorporate highvoltage IGBTs, require active cooling to prevent degradation of the passive circuit components. In these situations, a custom passive solution can be a better alternative compared to ‘making do’ with what is available. Custom component solutions are often the last choice of circuit designers. Conventional wisdom suggests custom devices should command higher prices, have a smaller supplier base, and have longer lead times. Demands for short design cycles and cost efficiency are often the most important factors that dissuade engineers from pursuing a custom component solution for a new design, and are usually more significant than any concerns about the suitability of the component for the application. KEMET has been working to make the development of custom passive solutions as efficient and cost-effective as possible, to enable engineers to be sure the most suitable components will be available at the right time and at a suitable price to meet their needs. At the heart of the initiatives is a commercial web-based application used by field applications engineers and sales professionals that are in frequent contact with circuit designers to capture critical technical design and componentcost requirements for leading-edge designs. The requirements are shared with key product design engineers and materials scientists to immediately start the design review process. The design review process routes the new design request through various stages to assess the technical feasibility, projected development costs, development lead time and manufacturing feasibility. If a component already exists that will satisfy the requirements, this process is able to identify the optimum parts and hence enables a rapid and economical solution. Where a standard part does not yet exist for the new application requirements, KEMET design engineers are ready to collaborate with circuit design engineers to develop a custom solution. The project follows a proven process, which first ensures that all technical, schedule and economic requirements are understood. The next step is to identify suitable existing materials and manufacturing capabilities at KEMET to develop a customized solution that makes the greatest possible use of readily available resources or any that may be currently in development for a wider market. KEMET has product development facilities in every major economic region of the world that support the entire passive component market. These facilities can be used to leverage all available KEMET resources to solve problems for customers. This approach reduces the cycle time for developing new parts, while at the same time aiding cost control and allowing rapid development of prototype samples. Having prototype samples available quickly allows circuit design engineers to begin testing their prototypes early in the project and hence devote more of their skills and attention to the difficult task of validating the new design. This approach offers the best opportunity to provide a solution in the time needed and meet the required cost targets. Customization delivers results An increasing number of customers’ design projects bring demands for bulk capacitance that has long life at temperatures and ripple currents over and above the capabilities of existing film and electrolytic capacitors. KEMET has developed the capability to manufacture multi-capacitor stacks in a variety of form factors that incorporate KEMET’s X7R (figure 1) and world-leading C0G and U2J ceramic dielectrics to be able to offer high capacitance in a package capable of operating up to extremely high temperatures (figure 2). KEMET has also extended its line of high-voltage ceramic capacitors to deliver an extremely small 1 kV capacitor. Building on this expertise enabled the development of a small case (2220) 10 kV surfacemountable C0G capacitor Fig. 2: A 4.2 μF 50 V rated U2J ceramic capacitor stack for surface mounting from KEMET. for use in portable X-Ray equipment, replacing bulkier highvoltage components and thus helping the customer create an instrument that is more lightweight and portable than any previously available. Everything FPGA. www.electronics-eetimes.com Electronic Engineering Times Europe March 2017 31


EETE MAR 2017
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