The recommended value for the output capacitor is 22 µF. Output capacitance above 100 µF needs to have a ESR of ≥ 10 mΩ for stable operation. The architecture of the TPSM82903 allows the use of tiny ceramic output capacitors with low equivalent series resistance (ESR). These capacitors provide low output voltage ripple and are recommended. To keep its low resistance up to high frequencies and to get narrow capacitance variation with temperature, use X7R or X5R dielectric. Using a higher value has advantages like smaller voltage ripple and a tighter DC output accuracy in power save mode (see the Optimizing the TPS62130/40/50/60 Output Filter application report).

In power save mode, the output voltage ripple depends on the output capacitance, its ESR, ESL, and the peak inductor current. Using ceramic capacitors provides small ESR, ESL, and low ripple. The output capacitor needs to be as close as possible to the device.

For large output voltages, the DC bias effect of ceramic capacitors is large and the effective capacitance must be observed.