CSD87381P: LFM and Nat Conv

Hi Nagata san,

Thanks for the inquiry. The curves in Figure 3 of the datasheet are generated from actual power loss and thermal data with the CSD87381P operating in a synchronous buck converter at the electrical conditions specified in Figures 1 & 2 and on a PCB described in section 5.6 of the datasheet. Natural convection means that there is no external forced airflow from a fan or blower. The LFM = linear feet per minute of forced airflow across the PCB from a fan or blower. This is typically measured with a hot wire anemometer at a location right above the board. The airflow helps with cooling the power block by promoting better heat transfer to ambient. Higher airflow (400LFM > 100LFM) allows the power block to operate at a higher ambient temperature for the same output current or at a higher output current for the same ambient temperature. I hope this adequately answers your question.