SNVS787I January 2012 – August 2021 LM5018
A coupled inductor or a flyback-type transformer is required for this topology. Energy is transferred from primary to secondary when the low-side synchronous switch of the buck converter is conducting.
The maximum inductor primary ripple current that can be tolerated without exceeding the buck switch peak current limit threshold (0.39 A minimum) is given by Equation 25.
A higher value of 47 µH is selected to ensure the high-side switch current does not exceed the minimum peak current limit threshold.