TPS54010: TPS54010

Lei
There are two different options for setting the switching frequency.
1. You can program the switching frequency to any frequency between 250 kHz and 700 kHz by connecting a resistor between RT pin and GND. Use equation 1 in the datasheet to calculate the resistor value. The SYNC pin is left open. In this case, the frequency is still generated internally, it is just programmed using an external resistor.
2. You can program the TPS54010 to operate at two different pre-programmed frequencies, 250 kHz or 550 kHz. Leave RT pin open. For 350 kHz operation leave the SYNC pin open or connect it to GND. For 550 kHz operation, pull SYNC up above 2.5 V.

The actual choice of switching frequencies is up to the user. Generally lower frequencies give higher efficiency but require physically larger output filter components. Higher frequencies yield smaller designs with somewhat lower efficiencies. You can set a mid range frequency as a compromise between efficiency and size. The preset frequencies allow you to save on one component in your BOM as no RT resistor is required.

For external frequency, you supply an external clock signal between 300 kHz and 700 kHz to the SYNC pin.