WEBENCH® Tools/WEBENCH-POWER-DESIGNER: DC Bias De-rated for Cout

na,


I am sure that the Webench tool is actually specifying multiple output capacitors, not a single 22 uF capacitor. It is not uncommon for the capacitance to rise a bit above the nominal value as the applied DC bias rises above 0 V. I personally used 2 x 22 uF ceramic capacitors for the output filter when I designed the TPS54239E EVM (you can see the schematic in the datasheet). The recommended capacitance is from 22 to 68 uF. It is intended to use one, two or three 22 uF, but it is a recommendation, not a requirement. It is ok to use other combinations. I would not be concerned with slightly higher values up to 100 uF total. I do not support that device any longer, but I was the original application engineer for that product family and have lots of experience with it. please post again if you have followup questions.