Hi Kai,
WEBENCH Power Designer is selecting the output capacitor to meet certain default load transient overshoot and undershoot specifications in addition to steady state output voltage ripple requirements. In reality, the WEBENCH capacitor selection may be conservative and more than you need in your application. For example, the EVM guide only shows 4 x 47uF capacitors. Table 5 on p. 22 in the datasheet outlines the min/max range of output cap values recommended, so you can use capacitance values in this range. In WEBENCH, if you want to choose a different capacitor, you can select an alternate part as shown below:
You can edit the capacitance minimum and target values to open up the selection of capacitors:
After choosing your desired capacitor you can go to the simulation page by clicking on
and run a load transient simulation to see the overshoot and undershoot performance with your chosen capacitor.
Regards,
Kris
