Following are the specifications used to design a 15.2V sensor power supply,
Vin = 24V ± 4%, Vout = 15.2V ± 4%, Iout = 90mA, fsw = 800KHz
Following are the component values used,
RFB1 = 1K, RFB2 = 11.5K, RON = 180K, L = 470uH, C = 9.4uF, Rr = 45.3K, Cr = 3.3nF, Cac = 10nF
Soft start circuit as given in datasheet is used.
An issue is observed in calculated and measured fsw. Typical calculation for fsw using equation 1 in datasheet is roughly 945KHz. And measured fsw for no load is 772KHz.
How accurate is equation 1 in the datasheet?
Is "9 x 10^-11" a constant? How is it derived?
