Step -1: X’fmr Turn rating
Input Voltage : 8 ~ 20Vdc
Max turn on duty : 76%
Lamp voltage : 700Vrms (w/o output cap.)
N = 700/ √(72*.76) = 113
Step -2 : Calculate Np
Np = Vin × ton/(B × Ae)
Where
Np = Minimum number of primary turns
Vin = Input voltage (volts)
ton = ON-time of the N-MOS switches (s)
B = Core flux density swing (tesla)
Ae = Smallest cross section area of the core where flux flows (mm2)