I already have a SMPS design book that I am learning from.
What is says to do is calculate a minimum primary inductance based on the input voltage, switching frequency, and peak current.
When this minimum inductance is calculated, choose an appropriate core (based on power requirements), then calculate the number of turns in the primary to achieve the minimum inductance. The N^2 = L/Al formula (which is in every ferrite calatlog ive seen).
The inductance factor (Al) is straight from the catalog, so when calculating the number of turns needed to reach that minimum inductance needed for the primary thats how I got the low number.
This design proceedure seems correct to me, where am I going wrong?