The ZXLD1350 is a free running hysteretic switching converter. The oscillator frequency is mainly controlled by the choice of inductor. As well as the inductance value, the frequency at which the ZXLD1350 oscillates depends on various other parameters including the input voltage and the difference between the input voltage and the output voltage, which is dependent on the number of LEDs being driven. The coil resistance and the LED current all alter the frequency. The equations will be shown later. There are other factors that can affect your choice of inductors. At the system level, consider what frequency you want use and if there are frequencies to be avoided. You need to consider electromagnetic interference and efficiency. These factors will affect the type of inductor you choose at the component level. The lower the frequency the higher the inductance value and the bigger physical dimensions the inductor will be. If EMC is a consideration choose a screened or shielded inductor.