For stable current loop operation and to avoid subharmonic oscillations, the slope capacitor should be selected based on Equation 26:

Equation 26.

This slope compensation results in “dead-beat” operation, in which the current loop disturbances die out in one switching cycle. Theoretically, a current mode loop is stable with half the “dead-beat” slope (twice the calculated slope capacitor value in Equation 26). A smaller slope capacitor results in larger slope signal which is better for noise immunity in the transition region (V_IN~V_OUT). A larger slope signal, however, restricts the achievable input voltage range for a given output voltage, switching frequency, and inductor. For this design, C_SLOPE = 220 pF is selected for better transition region behavior while still providing the required V_IN range. This selection of slope capacitor, inductor, switching frequency, and inductor satisfies the COMP range limitation explained in the Section 7.3.13 section.