For the best output and input voltage filtering, low-ESR ceramic capacitors are required. The input capacitor minimizes input voltage ripple, suppresses input voltage spikes, and provides a stable system rail for the device. The input capacitor must be placed between VIN and PGND as close as possible to those pins. For most applications, 22 μF is sufficient, though a larger value reduces input current ripple. The input capacitor plays an important role in the EMI performance of the system as explained in the Simplify Low EMI Design With Power Modules White Paper.

The architecture of the device allows the use of tiny ceramic output capacitors with low equivalent series resistance (ESR). These capacitors provide low output voltage ripple and are recommended. The capacitor value can range from 2 × 22 µF up to 150 µF. The recommended typical output capacitors are 2 × 22 µF or 1 × 47 µF with an X5R or better dielectric. Values over 150 µF can degrade the loop stability of the converter.

Ceramic capacitors have a DC-Bias effect, which has a strong influence on the final effective capacitance. Choose the right capacitor carefully in combination with considering its package size and voltage rating. Make sure that the effective input capacitance is at least 10 µF and the effective output capacitance is at least 22 µF.