I'm trying to use the NCP1014 (65kHz) to make a flyback converter. I'm using coilcraft's transformer B0570-BL which is specifically designed for the NCP1014, with turns ratio 1:0.06 or 16.67:1. I intend to take in narrow european mains (actually, narrow Indian mains, 230VAC ~ 310VDC) and generate 1A@12V.
Using the 'textbook' flyback controller equations, I get a duty cycle requirement using that transformer of:
dctyp = N * Vout / Vin
= 16.67 * 12.7 / 310 = 0.68
The datasheet of the NCP1014 uses its eq.24 on page 17 for operating duty cycle,
dc = Ip * Lp / Vin * Tsw
= (450mA * 3.4mH) / (310V * 15.38us)
= 0.321
The two duty cycles are very different. I understand why this is - the duty cycle for the NCP1014 is set only by the time it takes for primary current to ramp to 450mA. What I can't work out is how the output regulation will work for this, given that the required duty cycle is more than the cutoff.
Given the duty cycle the NCP1014 will cut off at, will the output have enough energy to sustain a stable 12V output? How does one make sure this will work for a given output voltage (12V, in this case)
I have attempted to work though the datasheet in nearly its entirety to the best of my understanding. I have put it up here, if it will help.