The datasheet for this converter does not specify a minimum SS capacitance. Nor does it define if a SS cap is required, however, on a new design I am doing, I only see this part function properly with the SS enabled rather than left floating. Can this be confirmed?
Hell Matta and welcome to the MPS Technical Forum. There is no minimum SS capacitance. If no SS cap is at the SS pin, then the pin will immediately be pulled up to the SS voltage and the device will switch at near current limit to bring up the output voltage very quickly. The data sheet equation #1 can be used to calculate a soft start capacitance value to ensure a smoother startup operation. If no SS capacitor is connected and the device is not starting properly, it is possibly going into overcurrent protection and repeating, depending on the conditions. In that case adding the SS capacitor should allow proper startup.