I'im designing a buck , 400W converting 32Vdc to 28Vdc. The circuit works almost well, but instead of 100kHz or so of the switching frequency I got only audible 3..5kHz, depending of the load. Output voltage is maintained well, so feedback works properly. Main inductance is 5uH wound on the MPP toroid with appr. 1 inch diameter.
Why the reality differs so much from Ltspice simulation ?