Other Parts Discussed in Thread: TPS60403
I have an appplication, that is sensitive to switching frequencies at about 10 bis 20 kHz. I uses the LM2667, which as a fundamentel switching frequency of 2MHz. In my application, the load of the LM2667 is very light, so that the pulse frequency modulation is working. Consequently, the LM2667 switched only a few pulses with 2MHz, afterwards it waits for about 70us (13kHz). This 13kHz frequency disturbs the signal of my ciruit. I can set the LM2667 to a continuous switching mode, if I reduce the flying capacitor to just 10 or 20nF. Althogh, in the datasheet of the LM2667 is mentioned that the flying capacitor C1 should not be less then 200nF. What is the reason for this minimum value of the flying capacitor?
Thanks for your help.