The TPS62933F device requires an input decoupling capacitor and, depending on the application, a bulk input capacitor. The typical recommended value for the decoupling capacitor is 10 μF, and an additional 0.1-μF capacitor from the VIN pin to ground is recommended to provide high frequency filtering.

The value of a ceramic capacitor varies significantly over temperature and the amount of DC bias applied to the capacitor. X5R and X7R ceramic dielectrics are recommended because they have a high capacitance-to-volume ratio and are fairly stable over temperature. The capacitor must also be selected with the DC bias taken into account. The effective capacitance value decreases as the DC bias increases. The capacitor voltage rating needs to be greater than the maximum input voltage. The input capacitor must be large enough to limit the input voltage ripple, see Equation 24.

Choosing ΔV_IN= 0.2 V gives a minimum of C_IN= 4.9 μF. Considering derating, two standard value 10-μF, 50-V capacitors are selected for better input ripple performance. Another 0.1μF capacitor has been added as a bypass capacitor to clear high-frequency noise.

Energy is transferred from primary to secondary when the synchronous switch of the buck converter is on. The primary output capacitance is given by Equation 25.

Choosing ΔV_OUT1= 0.05 V gives a minimum of C_OUT1= 19.2 μF. Considering derating, two standard value 22-μF, 35-V capacitors are selected.

The secondary output current is sourced by C_OUT2 during T_ON. Ignoring the current transitions time in the secondary winding, the value of the secondary output capacitor can be calculated using Equation 26.

Choosing ΔV_OUT2= 0.05 V gives a minimum of C_OUT2= 4 μF. Considering derating, two standard value 10-μF, 50-V capacitors are selected, the same as the C_OUT3.