SNVS787I January 2012 – August 2021 LM5018
At the minimum input voltage, the maximum switching frequency of the LM5018 is restricted by the forced minimum off-time (TOFF(MIN)) as given by Equation 10.
Similarly, at maximum input voltage, the maximum switching frequency of LM5018 is restricted by the minimum TON as given by Equation 11.
Resistor RON sets the nominal switching frequency based on Equation 12.
Operation at high switching frequency results in lower efficiency while providing the smallest solution. For this example, 440 kHz was selected, resulting in RON = 253 kΩ. A standard value for RON = R3 = 237 kΩ is selected.