To get high power density with a very small solution size, a high switching frequency allows the use of small external components for the output filter. However, switching losses increase with the switching frequency. If efficiency is the key parameter, more than solution size, the switching frequency can be set to half (1.25 MHz typical) by pulling FSW to High. It is mandatory to start with FSW = low to limit inrush current, which connecting FSW to V_OUT or PG can accomplish. Running with lower frequency produces higher efficiency, but also creates higher output-voltage ripple. Pull FSW to low for high-frequency operation (2.5 MHz typical). To get low ripple and full output current at the lower switching frequency, the recommended minimum inductor value is 2.2 µH. An application can change the switching frequency during operation, if needed. An internally-connected pulldown resistor of about 400 kΩ on this pin acts the same way as one on the DEF pin (see Section 8.3.4).