Project Analog - February 2009 - (Page 12) Understanding the Buck Switchmode Power Converter inTroducTion Contents Viewpoint Selecting the Right dc/dc Converter Selecting the Right Battery System Understanding the Buck Switchmode Power Converter Analog news An excerpt from Application Note AN793 “Power Management in Portable Applications: Understanding the Buck Switchmode Power Converter” Powering today’s portable world poses many challenges for system designers. The use of batteries as a prime power source is on the rise. As a result, a burden has been placed on the system designer to create sophisticated systems utilizing the batteries full potential. Each application is unique, but one common theme rings through: maximize battery capacity usage. This theme directly relates to how efficiently the energy from the batteries is converted and transferred to the system load. No single method is ideal for all applications. Linear regulators, switched capacitor charge pumps, and inductor based switchmode power converters are all employed. Each method has its associated advantages and disadvantages. It is the particular application with its individual requirements that determines which method will be the best to use. This article focuses on the fundamentals of inductor based switchmode power converters. This is a “grass roots” approach to understanding switchmode power converters. Specifically, the basic buck circuit topology and its associated waveforms will be examined both empirically and mathematically. All known switchmode power converters can be derived from combinations of the basic buck and/or boost converters along with some form of transformation function. Roughly 85% of today’s switchmode power converters are derived from the buck topology. Understanding its operation is essential to switchmode power converter design. 12 · PRojeCt ANAlog · VolUme 3 / NUmBeR 1 12 · PRojeCt ANAlog · VolUme 3 / NUmBeR 1 Microchip analog page Sample center microchipDIRECT Reference designs/ app notes Technical training http://www.microchip.com http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=79&redirects=analog http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=79&redirects=analog http://sample.microchip.com/Default.aspx?testCookies=true http://www.microchipdirect.com/catalogselection.aspx?returnURL=default.aspx http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1423
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