SLVSFM1 March 2021 TPS62902
The devices of the TPS62902 family are internally compensated to be stable with L-C filter combinations corresponding to a corner frequency to be calculated with Equation 16:
Proven nominal values for inductance and ceramic capacitance are given in Section 18.104.22.168 and are recommended for use. Different values can work, but care has to be taken on the loop stability which is affected. More information including a detailed LC stability matrix can be found in SLVA463.
The TPS62902 devices include an internal 3-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 Equation 17 and Equation 18:
Though the TPS62902 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, improved transient response, or both. An external feedforward capacitor can also be added. A more detailed discussion on the optimization for stability versus transient response can be found in SLVA289 and SLVA466.