Using TOP Swithch without opto isolation
Hello.
I try to compose DC-DC power supply with 150...200 V input and 27 V output.
Output power is about 30W. 40W peak.
The power supply design not need a halvanic insulation between primary and secondary parts.
Could you please infrom me about possibility of design flyback converter based on TOP258YN with feedback without optocoupler insulation.
I am sorry for my bad english. :(
Comments
Dear Sir/Madam
According to pages 5 & 6 of AN-32, there are 4 types of feedback circuits for TOPSwitch. The function of Opto/Zener & opto/TL431 is clear for me, because they get sample from Vo & transfer it to pin C. However, the function of pri/basic & pri/enhanced isn't clear for me, because they don't get any sample from Vo . Would you please explain how these pri feedback circuits work & regulate the output voltage?
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Hi Ahja,
Thank you for your interest in Power Integrations' part.
Regarding your question, basically the Vo is in proportion with bias feedback winding regulation since they are both in flyback with the primary winding. We usually called this cross regulation. This is indirect sensing of Output voltage that is why it has wider tolerance regulation compared to opto-zener feedback circuti which directly sensed the output. I hope this answers your question. Thank you.
Take a look at the feedback circuit as synthesized in this document. It does not use an optocoupler...
http://www.powerint.com/sites/default/files/PDFFiles/der30.pdf