SNVSB28 December 2017 LM25575-Q1
RT sets the oscillator switching frequency. Generally, higher frequency applications are smaller but have higher losses. Operation at 300 kHz was selected for this example as a reasonable compromise for both small size and high efficiency. The value of RT for 300 kHz switching frequency can be calculated Equation 4:
The nearest standard value of 21 kΩ was chosen for RT.