trying to understand the feedback in sg3525 circuit

[hamid159]

hy everyone, i've a problem in the given circuit.i wanna know how feedback is acting in this circuit.how node 7,10,11,12 will affect the output of pwm.

- - - Updated - - -

15 and 13 pin of pwm are connected to each other.

 

[goldsmith]

hy everyone, i've a problem in the given circuit.i wanna know how feedback is acting in this circuit.how node 7,10,11,12 will affect the output of pwm.

- - - Updated - - -

15 and 13 pin of pwm are connected to each other.

Hi Hamid
Sorry but your diagram seems a bit unclear . what you mean by out put PWM ? do you mean duty cycle of the voltage across the secondary winding ?
Your drawing is a bit confusing ! feedback of that circuit must bee taken from out put of your transformer and of course after it be rectified and filtered !

Best Wishes
Goldsmith

 

[hamid159]

I'm talking about the frequency of pwm.actually this transformer acting as somehow gate transformer.i've a class b ouput stage after it that will derive the two half bridge mosfets.whose output (after power transformer and rectification stage ) will be fed into node 11 and 7 by optocoupler.let talk about node 11.if the output of optocoupler is fed into this node.what i mean is what happened if output voltage of the supply drop or increase? .what is the purpose of dual diode in Rt pin sg3525? i thnk change in voltage at pin 11 will affect the Rt,and so frequency will change.but how change in voltage at node 11 will affect the Rt?