I am planning to design smps power supply that using flyback topology. It will have 12V@5A output values. But it is not clear for me how to estimate input power. It will supply from 220 AC input port. I am trying to find it from my transformer inductance which is 75uH. It is logical to find from V=Lxdi/dt ? My switching frequency is 100kHZ and will work %45 duty cycle. Therefore ramp signal rises to peak current in 4.5us. I have some ideas like this. Can u help me how to find input power and from there eff?