F_s and R_ON: Unless the application requires a specific frequency, the choice of frequency is generally a compromise because the size of L1 and C2, and the switching losses are affected. The maximum-allowed frequency, based on a minimum on-time of 250 ns, is calculated by Equation 6:

For this exercise, F_MAX = 444 kHz. From Equation 2, R_ON calculates to 180 kΩ. A standard-value, 237-kΩ resistor is used to allow for tolerances in Equation 2, resulting in a nominal frequency of 337 kHz.