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[FAQ] TPS568230: TPS568230 D-CAP3 converter inductor selection

Part Number: TPS568230

Hi,

The inductor selection is an important part of buck converter design. The inductor selection affects efficiency, output ripple, load transient response and control loop stability. Typically for most buck converters, the inductor value is selected to keep the ripple current between 20%-40% of full load current. 

However, for TI D-CAP3 converters with internal loop compensation, the inductor selection should follow the table of recommended component values in the datasheet. D-CAP3 architecture generates an internal ramp which is fed to the FB pin to emulate output voltage ripple, enabling the use of low ESR output capacitors. Thus, the D-CAP3 converters need certain amount of inductor ripple current to stabilize the loop. 

For example, TPS568230 needs around 2.0A-2.5A peak to peak ripple current from the Table 3 of datasheet. Please note table 3 recommended inductor values are based on 12V input voltage. If the application is 5V input, or different output voltages which are not listed in the Table 3, please use below equation to re-calculate the inductor values. 

        

Thanks,

Nancy