sg3524 error amplifier - how to isolate it..?

[s.manikandan]

Actually there is '-' ,'+', and comp terminals for sg3524 pwm controller.. i m designing isolated converter for our application. i need to isolate the voltage sensing which is given to '-' terminal of the error amplifier.. how to acheive it..? any idea or example circuit..?

Usually i used to go with tl431 and optocoupler at the feedback side to flow current into the error amplifier to control pwm..

but how to achieve in sg3524 isolated feedback....?

 

[goldsmith]

Actually there is '-' ,'+', and comp terminals for sg3524 pwm controller.. i m designing isolated converter for our application. i need to isolate the voltage sensing which is given to '-' terminal of the error amplifier.. how to acheive it..? any idea or example circuit..?

Usually i used to go with tl431 and optocoupler at the feedback side to flow current into the error amplifier to control pwm..

but how to achieve in sg3524 isolated feedback....?

Hi s.manikandan
In SG3525 you have an op amp and your hands are more open because input terminals are in your access . so first you should configure it as an error amplifier . it means you'll need a reference voltage and then a feedback path . so it can be harvested with an opto coupler and TL431 easily .
Best Wishes
Goldsmith

 

[s.manikandan]

Hi s.manikandan
In SG3525 you have an op amp and your hands are more open because input terminals are in your access . so first you should configure it as an error amplifier . it means you'll need a reference voltage and then a feedback path . so it can be harvested with an opto coupler and TL431 easily .
Best Wishes
Goldsmith

Thank you for your quick response. find the attached image..

Fine about your explanation, i have designed '+' terminal as reference voltage 2.5V , '-' terminal as feedback output voltage which is taken by voltage divider resistor , 'comp' pin & '-' terminals are error amplifier type 2 parameters ..

Now closed loop is achieved but isolation is not.. but how can isolate output voltage( voltage divider) and '-' terminal of sg3524..

 

[goldsmith]

Thank you for your quick response. find the attached image..

Fine about your explanation, i have designed '+' terminal as reference voltage 2.5V , '-' terminal as feedback output voltage which is taken by voltage divider resistor , 'comp' pin & '-' terminals are error amplifier type 2 parameters ..

Now closed loop is achieved but isolation is not.. but how can isolate output voltage( voltage divider) and '-' terminal of sg3524..

Hi again
Well , i've improved your schematic for isolated feedback . take a look here , please :



Best Wishes+Good Luck
Goldsmith

 

[s.manikandan]

Hi again
Well , i've improved your schematic for isolated feedback . take a look here , please :



Best Wishes+Good Luck
Goldsmith

thank you very much again.

very clear explanation through diagram. first I will work out it and let you know our thought.