Other Parts Discussed in Thread: UCC28600, LM5023, UCC28711, UCC28701
Hi TI team,
My company is looking for QR flyback IC and wants me to search for some useful solution, and I read some documents from TI.
I have some questions about UCC28610 (Frequency and Peak Current Modulated), I am trying to use a QR flyback IC, and I read the TI's document "Exposing the Inner Behavior of a
Quasi-Resonant Flyback Converter" and I have some questions would like to ask you guys. please see my below questions, thanks.
1.) After reading this document, I am still confused about "Frequency Modulated, Constant Current" or "Frequency and Peak Current Modulated"? Could you please provide an example to me?
From my understanding, we have different input voltage, so the peak current will be different, IC will detect my peak current and modify the switching frequency to implement the QR mode. if yes, why we don't just modify the switching, why we need to also do the peak current modulate?
2.) What does this mean "As the output load decreases, the peak current decreases. This makes it very difficult to calculate the switching frequency and peak current at any specific operating point" Could you please provide an example to me?
3. in the FFM, why does the peak current need to help constantly?
4. I don't understand Figure 10 why FFM is between the mid load and high load, as my understanding, FFM is for light load use to improve the light load efficiency. compare with Figure 9, this is more reasonable to me, and why Figure 10 doesn't have TM mode? Figure 10 can't achieve the QR? because, from figure 2, only TM mode can have lower Vds.
5. In what situation I will need to use "Frequency Modulated, Constant Current" IC or "Frequency and Peak Current Modulated" IC?
Sorry for asking too many questions, but I need to understand them before I use them, hope TI's members could give me some suggestions, thanks.