Selecting output capacitors for the boost regulator

A boost output capacitor (CVINT) on the VINT pin is essential for stability and operation. A capacitor with an effective capacitance of at least 3.5 µF is required.

When selecting a capacitor, consider the effects of DC bias voltage, tolerance, and temperature behavior. The voltage rating should be higher than the maximum output voltage of the boost regulator with at least 6.3 V recommended. For RF sensitive applications, place an additional 1 nF to 100 nF decoupling capacitor parallel to CVINT.

For the VOUT pin, a 2.2 µF output capacitor (COUT) is recommended with a minimum requirement of 0.7 µF effective capacitance.

Additional capacitance can be added to the VINT pin depending on factors like the use case, battery, and load. Increasing CVINT capacitance can improve load transient response and efficiency in hysteretic Ultra-Low Power (ULP) or Low Power (LP) mode and reduce the ripple in High Power (HP) mode.

If additional bulk capacitance is needed on the output, it is better to place it on the VINT pin rather than VOUT. This placement avoids the need to charge or discharge high capacitance on VOUT during different operation modes, such as Hibernate mode, where VINT remains regulated while VOUT is switched on only during the active state.

The following tables show examples of capacitor models for CVINT and CVOUT.