Tool/software:
HI,
I belive that my BMT limits are set correctly (0.6).
I not able to use option 7 - disable burst mode because it goes to OVP.
I suspect that its problem of transformer design (and my requirement) and switching frequency or basicly primary side.
It seems to me that even that small amount of energy (in burst mode) is enough to charge output capacitor an cover needed load current. Frequency in burst mode is 170 kHz that should be also ok (relatively high).
If I increase frequency, there is more losses in transformer (more heat generation), but burst mode end quickly (with 300 mA load). Problem is that it is designed for 100 kHz, but in that case transformer frequency is almost 500 kHz and gets hot quickly (80 °C in few minutes).
Only component that is lossy is transformer and secondary side rectification diodes during load. Transistors and other components are cold.
How to reduce energy transfer with same transformer or how to change transformer design?
What did I missed in transformer design stage? Is better to have high or lower Ln ratio? I set it to 6 (Llk 84 uH and Lp 504 uH) as it was chosen in demoboard with output 12V/15A.
