SLVSDG6B May 2016 – April 2021 TPS54302
Use Equation 8 to calculate the minimum value of the output inductor (LMIN).
In general, the value of KIND is at the discretion of the designer; however, the following guidelines may be used. For designs using low-ESR output capacitors, such as ceramics, a higher KIND can be used. When using higher ESR output capacitors, KIND = 0.2 yields better results.
For this design example, use KIND = 0.35. The minimum inductor value is calculated as 9.78 μH. For this design, a close standard value of 10 μH was selected for LMIN.
For the output filter inductor, the RMS current and saturation current ratings must not be exceeded. Use Equation 9 to calculate the RMS inductor current (IL(RMS)).
Use Equation 10 to calculate the peak inductor current (IL(PK)).
Smaller or larger inductor values can be used depending on the amount of ripple current the designer wants to allow so long as the other design requirements are met. Larger value inductors have lower AC current and result in lower output voltage ripple. Smaller inductor values increase AC current and output voltage ripple.