Hi. I am trying to implement QR flyback converter. With ICE5QSAG, Würth Elektronik transformer. My application is taken from AN_201609_PL83_024.
So i am trying to run this circuit. But IC auto restarts continously. I could get 12 V and 5 V and burst mode was closed (opto's transistor side, dull down 25k). with light load (eg 60 mA) But if i take the load IC restarts, if i connect 12W load it restarts...
I think problem about burst mode or feedback.
Auto restart mode protection states:
• Vcc over voltage
• Vcc under voltage
• Open loop / over load
• Over temperature
• Limited charging current for Vcc to GND
Detailed measurements in PDF.
Hi @hasanyucelcogal ,
Thank you for posting in Infineon Community.
AN_201609_PL83_024 is designed for dual output with cross-regulated loop feedback. It may not operate properly if loading is applied only to a single output.
Protection is one of the major factors to determine whether the system is safe and robust.
Your understanding on auto restart modes is accurate.
Can you provide more details to analyze the issue
1. CS pin voltage. (Even for Vcs < 0.1V. IC will auto restart)
2. Voltages and waveform at Vcc, FB, ZCD.
3. Please check which protection is being activated.
4. while you are loading on 12V, any changes in output voltages?
1- For CS pin voltege i need to pull power. if i pull power from output it restarts (60 ma OK but 1A it restarts).
2- You can check detailed document that i've upload for scope screenshots.
3- Couldn't find yet. That is the problem.
4- If 12V open it restarts. İf i pull 50-60 mA it gives continuously. When output current about 1A it restarts. My circuit infineon's app note. they are same as switch, transformer and mosfet.
I apologize for the delayed reply.
Reviewing waveforms indicated that voltage at VIN around 2V is appropriate.
The gate waveform appears to have constant voltage, and even ZCD is constant. This implies there isn't any switching. since the Vcc capacitor is charged at start-up through Rstartup. You are sensing Vcc voltage. Then voltage from the auxiliary winding should take over from there. Which is not happening.
Can you confirm this with the drain and gate waveform on a single screen?