JAJSFE6I July 2009 – May 2018 TPS65070 , TPS65072 , TPS65073 , TPS650731 , TPS650732
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
The step-down converters operate typically with 2.2-µH output inductor. Larger or smaller inductor values can be used to optimize the performance of the device for specific operation conditions. The selected inductor has to be rated for its DC resistance and saturation current. The DC resistance of the inductance will influence directly the efficiency of the converter. Therefore an inductor with lowest DC resistance should be selected for highest efficiency.
Equation 4 can be used 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 as calculated with Equation 4. This is recommended because during heavy load transient the inductor current will rise above the calculated value.
where
The highest inductor current will occur at maximum Vin.
Open core inductors have a soft saturation characteristic and they can usually handle higher inductor currents versus 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. It must be considered, that the core material from inductor to inductor differs and will have an impact on the efficiency especially at high switching frequencies.
Refer to Table 11 and the typical applications for possible inductors.
INDUCTOR TYPE | RECOMMENDED MAXIMUM DC CURRENT | INDUCTOR VALUE | SUPPLIER |
---|---|---|---|
LPS3010 | 0.6 A | 2.2 µH | Coilcraft |
LPS3015 | 1.2 A | 2.2 µH | Coilcraft |
LPS4018 | 1.5 A | 2.2 µH | Coilcraft |
VLCF4020 | 1.5 A | 2.2 µH | TDK |