SLVSB64I November 2011 – March 2018 TPS65217
The step-down converters operate typically with 2.2-µH output inductors. Larger or smaller inductor values can be used to optimize the performance of the device for specific operation conditions. The selected inductor must be rated for its dc resistance and saturation current. The dc resistance of the inductance directly influences the efficiency of the converter. Therefore, an inductor with the lowest dc resistance should be selected for highest efficiency.
Use Equation 4 to calculate the maximum inductor current under static load conditions. The saturation current of the inductor should be rated higher than the maximum inductor current, because, during heavy load transients, the inductor current increases to a value greater than the calculated value.
The highest inductor current occurs at maximum input voltage (VIN). Open-core inductors have a soft saturation characteristic and can usually support greater inductor currents than a comparable shielded inductor.
A more conservative approach is to select the inductor current rating just for the maximum switch current of the corresponding converter. The core material must be considered because it differs from inductor to inductor and has an impact on the efficiency, especially at high switching frequencies. Also, the resistance of the windings greatly affects the converter efficiency at high load. Table 35 lists the recommended inductors.
|PART NUMBER||SUPPLIER||VALUE (µH)||RDS (mΩ) MAX||RATED CURRENT (A)||DIMENSIONS (mm)|
|LQM2HPN2R2MG0L||Murata||2.2||100||1.3||2 x 2.5 x 0.9|
|VLCF4018T-2R2N1R4-2||TDK||2.2||60||1.44||3.9 x 4.7 x 1.8|