Azhar Ali Chohan wrote:
-------------------------------
Hi!
1, The topology i am using is flyback.


Azhar,

I salute your persistence !

I am not an expert in SMPSU design but consider the following:
Start by considering the frequency of operation and power required.In a flyback supply, the energy to be transferred is only loaded during the charging cycle, and delivered during the discharge cycle.

Energy will be stored in an inductor. The energy stored is given by E=0.5 * L*i^2

Consider how long the charging current has to "charge" the inductor. Consider too that this current, when it reaches its peak value MUST NOT saturate the transformer. Now with the energy stored in the inductor, the turns that will make the TX have the terminal inductance you need. Now consider the saturation current again. Your turns ratio is now also determined from the primary turns.

Now consider heat dissipation in your windings, and the packing density in the windings. For best efficiency, the wires should be as heavy as possible and fill the transformer,

Just the beginnings.

Steve


2, Question:- Is there any kind of limit like if core size is ABC then it can give this much power and if its size is DEF then it can give this much power...

Yes, and it relates to frequency, transfer ratio and current level.

3, Does operating frequency also changes maximum power transfer limit.
4, I have plan to use 89c2051 for controlling but initially i am playing with simple transistor oscillator. I want to use 89C2051 because i want to show the output voltage on seven seg. display and also want to control the supply by serial com. i think this MCU is capable of doing this.

Thanks!