Scoping Out the Best DC-DC Converter Design

Focus:

When considering embedded dc-dc converter solutions, finding the optimum design is not a simple matter even if you've narrowed your search to a single power IC vendor. For a given set of power supply input and output requirements, there may be 50 or more possible designs. To determine which design works best in the application, designers need to establish goals for their power supply such as low cost, small footprint or high efficiency. Unfortunately, these goals are frequently in conflict with each other, adding to the complexity of finding the right solution. To address these challenges, semiconductor vendors are developing product selection tools that go beyond simple parametric searches and look-up tables, crossing into the realm of power supply design. This article demonstrates how to use one such tool, National Semiconductor's WEBENCH Visualizer, which which allows real-time comparison between a large number of power supply design options. As a design example, the article starts by specifying a buck converter with a 14-V to 22-V input range and a 3.3-V output at 2 A. Visualizer is then used to generate graphs showing the different design combinations possible with National's ICs and external components. The design options are plotted on graphs showing component footprint, efficiency and BOM cost for each solution. Visualizer settings are changed to show different perspectives on the results, and to show different sets of solutions optimized for different parameters, and the various results are explained. The discussion helps to explain obvious and not-so-obvious tradeoffs in dc-dc converter design.

What you’ll learn:

• How to use Webench Visualizer to quickly explore design tradeoffs among dc-dc converter solutions based on National Semiconductor's ICs
• How to graphically explore the possible tradeoffs in cost, footprint, and efficiency when designing nonisolated dc-dc converters

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Author & Publication:

Jeff Perry, National Semiconductor, Santa Clara, Calif., How2Power Today, Apr 30 2010

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