Why Choose Polymer Electrolytic Output Capacitors for Maximum Ripple Capability and Reliability Performance within eGaN based POL Converters

POL converters are met more and more often in many electronic systems. Their important requirements are a stable output voltage with load current variation, good temperature stability, low output ripple voltage and high efficiency and reliability. If the electronic system must be a portable one, small footprint and volume are also important factors which recently are well acomplished by eGaN transistor technology. Recent studies shows that the POL (Point of Load) converter's output capacitor is a paramount component from the reliability point of view, so a careful selection of it is determining the overall converters parameters. This paper provides how different technologies of output capacitor used in eGaN based POL buck converter determine the best performances. A setup based on EPC's eGaN FET transitor enclosed in 9059/30V evaluation board with a 12Vinput voltage/1.2Voutput voltage was tested. By measuring the output ripple's voltage and a thermal scanning based reliability calculus the behaviour of different output filter capacitor technologies is investigated.