9.2.2.2 Switching Frequency Selection

Select a switching frequency for the TPS543B20. There is a trade off between higher and lower switching frequencies. Higher switching frequencies may produce smaller solution size using lower valued inductors and smaller output capacitors compared to a power supply that switches at a lower frequency. However, the higher switching frequency causes extra switching losses, which decrease efficiency and impact thermal performance. In this design, a moderate switching frequency of 500 kHz achieves both a small solution size and a high efficiency operation is selected. The device supports continuous switching frequency programming; see Equation 4. additional considerations (internal ramp compensation) other than switching frequency need to be included.

Equation 4.

In this case, a standard resistor value of 40.2 kΩ is selected.