SG3525 ferrite transformer calculation

[maxpayne]

I am designing a 300W car amplifier using TAS5630B. To power the chip I am stepping up the 12V input to 40V DC using push-pull topology. My controller chip is SG3525 and I am using a PC40 material T28X16X16 size torroidal transformer.

For SG3525, I choose Rt= 22K, Ct= 1nF and Rd= 56 Ohms. Which gives oscillator frequency of 64KHz. So each MOSFET is switching at 32KHz.

My question is during calculation of primary turn of torridal transformer which frequency, f I have to consider in the formula Npri= (VinX10^8)/(4XfXBmaxXAc)? 32Khz or 64 Khz ?

 

[blasphemy000]

Use the switching frequency of 32KHz. That is the frequency that the transformer will be running at. The 64KHz is just the frequency of the internal oscillator in the SG3525.