SWCS142 July 2018 TPS650861
PRODUCTION DATA.
Placement of an inductor is required between the external FETs and the output capacitors. Together, the inductor and output capacitors make the double-pole that contributes to stability. In addition, the inductor is directly responsible for the output ripple, efficiency, and transient performance. As the inductance used increases, the ripple current decreases, which typically results in an increased efficiency. However, with an increase in inductance used, the transient performance decreases. Finally, the inductor selected must be rated for appropriate saturation current, core losses, and DC resistance (DCR).
Equation 1 shows the calculation for the recommended inductance for the controller.
where
With the chosen inductance value, the peak current for the inductor in steady state operation, IL(max), can be calculated using Equation 2. The rated saturation current of the inductor must be higher than the IL(max) current.