The output capacitor is responsible for filtering the output voltage and supplying load current during transients. Capacitor selection depends on application conditions as well as ripple and transient requirements. Best performance is achieved with a parallel combination of ceramic capacitors and a low-ESR SP™ or POSCAP™ type. Very low ESR capacitors such as ceramics reduce the output ripple and noise spikes, while higher value electrolytics or polymer provide large bulk capacitance to supply transients. Assuming very low ESR, Equation 16 determines an approximation to the output voltage ripple.

Equation 16.

Typically, a total value of 100 µF or greater is recommended for output capacitance.

In applications with V_out less than 3.3 V, it is critical that low-ESR output capacitors are selected. This will limit potential output voltage overshoots as the input voltage falls below the device normal operating range.