POL DC-DC Converter Output Capacitor Bank’s Reliability Comparison using Prediction Standard MIL-HDBK-217F and SN 29500

Abstract

A higher level of reliability became a compulsory demand in modern DC-DC converters [4]. Since the latest version MIL-HDBK-217F Notice 2 released in 1995 [1], newer failure rate prediction standards had appeared on the electronic systems reliability market. These are introduced to compensate for the lack of the newest component technology in the above-mentioned standard. When it comes to reliability many studies have shown that the output capacitor bank is demonstrated to be the most critical component [3]. In this work, the failure rate of an output capacitor bank used within a high current low voltage buck converter is calculated both by the latest prediction standard SN 29500 and by with the previous standard MIL-HDBK, providing a comparison between the two which is a helpful tool for the output capacitor selection in the early stage design. The components’ environmental conditions were defined by a standard POL buck converter used for both calculation methodologies. Results are compared by taking account of the influence of the component’s temperature and application of specific parameters such as temperature cycles.