JAJSM34F December 2012 – May 2021 LM25017
PRODUCTION DATA
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 (0.7 A minimum) is given by Equation 22.
Using the maximum peak-to-peak inductor ripple current ΔIL1 from Equation 22, the minimum inductor value is given by Equation 23.
A higher value of 100 µH is selected to insure the high-side switch current does not exceed the minimum peak current limit threshold. With this inductance, the inductor current ripple is ΔIL1= 90 mA at the maximum VIN.