The devices of the TPS6215x family are internally compensated to be stable with L-C filter combinations corresponding to a corner frequency to be calculated with Equation 12:

Equation 12.

Proven nominal values for inductance and ceramic capacitance are given in Table 9-2 and are recommended for use. Different values can work, but care must be taken on the loop stability, which is affected. More information, including a detailed L-C stability matrix, can be found in the Optimizing the TPS62130/40/50/60 Output Filter Application Report.

The TPS6215x devices, both fixed and adjustable versions, include an internal 25-pF feedforward capacitor, connected between the VOS and FB pins. This capacitor impacts the frequency behavior and sets a pole and zero in the control loop with the resistors of the feedback divider, per equations Equation 13 and Equation 14:

Equation 13.

Equation 14.

Though the TPS6215x devices are stable without the pole and zero being in a particular location, adjusting their location to the specific needs of the application can provide better performance in power-save mode and/or improved transient response. An external feedforward capacitor can also be added. A more-detailed discussion on the optimization for stability versus transient response can be found in the Optimizing Transient Response of Internally Compensated dc-dc Converters With Feedforward Capacitor and Using a Feedforward Capacitor to Improve Stability and Bandwidth of TPS62130/40/50/60/70 application reports.