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Using optocoupler for feedback to provide isolation

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saurav_sdpl

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I am designing an smps with 5V/200mA output using LNK305, the reference design

shown at powerint site doest have any isolation between primary and secondary.

If i use a optocoupler for feeding back the output signal to input can my opto provide at leat 6KV of isolation between primary ground and secondary ground
 

Re: opto-feedback

To ensure isolation between input and output you not only need isolation in the feedback path, but also in the power path .. see picture below ..
And one more thing, linear feedback optoisolator is not a good idea ..
See "CONTROL" in this website:
**broken link removed**

Regards,
IanP
 

opto-feedback

If the optocouples is rated for 6kV, it will provide 6kV isolation barrier that you want in the feedback path. Your schematic shows the part number PI-3796-121903, but I couldn't find the datasheet for the optocoupler with Google.
 

Re: opto-feedback

Thanx a lot for the clarification, but if i am using an opto-isolator i think i am isolationg the power ground with low power ground.

Now if i conduct a surge test of 2KV , whether optocoupler would be able to provide full isolation to the secondary side of SMPS.

If it could provide, then my transformer designing complexity will reduce if not wat could be the alternate solution
 

Re: opto-feedback

saurav_sdpl said:
...but if i am using an opto-isolator i think i am isolationg the power ground with low power ground.
Click to expand...
Your circuit diagram shows only one ground. To really split the grounds, you need a transformer, not just inductor.
 

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