What is the main use of optocoupler when we give feedback in SMPS?

[saurav_sdpl]

Wat is the main use of optocoupler when we give feedback in SMPS , is it just to provide isolation or else.

How does the opto circuit operate withj tiny switch IC, and how the resistance value calculated

urgent

 

[cameo_2007]

Re: optocoupler

opto coupler is used for the isolation between the input high voltage side and the low output side.
it controls the tiny swithching frequency.the output of the opto is connected to the EN pin of the TNY.the output current of the photo opto coupler,ie the current through the output diode of opto is controlled by the input voltage of the opto,ie nothing but the voltage fed back from the output.
thus the feed back voltage controls the current in the opto-output,the current drawn from the EN pin of TINY,which inturn controls the switching frequency.
can refer the application notes given in www.powerint.com

Added after 9 minutes:

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[bluesmaster]

Re: optocoupler

here is attachment

 

[bluesmaster]

Re: optocoupler

chinese verison

 

[hakeen]

Re: optocoupler

Optocupler do two main tasks (simultaneously):

Insulation: Galvanic Seperation of High-Low Voltage parts of a system

Isolation: Putting noise and external interferences out of system (CMR performance)., which is very important in industrial applications

Cheers