how to design two isolated power using TNY series

Do you mean you need a power supply with two outputs isolated one from the other?
If so, you use one winding for each output. You take the feedback from only one output.

Hi,
But in that case primary side would not be able to detect power drawn from non feedback winding ?
Do you have any such reference design or application note something ?

Regards,

You are right. One output is unregulated. Do you need tight regulation on both outputs? With one Output regulated and the other unregulated, there is still some regulation because the magnetic coupling of the secondary windings. If you wind the two secondary windings in parallel at the same time, the coupling is better.
The variation of the unregulated output will depend how both outputs are loaded. If the regulated output is at max load while the unregulated output is completely unloaded., then the unregulated output voltage will be very high. However if both loads are steady at max load, you may always have both output stable.
Another trek is to connect a zener or a preload at the unregulated output to avoid the voltage to go too high. We do not have any demo board for this kind of application

What would be the tranformer parameters turns etc ? Would you please paint a quick drawing indicating the values for the parameters of the power supply given in the first message?

Regards

We do not have a example design for this application.
You create a PI expert design. Then instead of winding the secondary the way PI expert tells you to do, You wind two separated windings. When you wind them, you handle the two wires in parallel as if they were a single winding. Then wind the two wires in parallel at the same time. This way each turn of each secondary will be very close to each other and the two windings will tend to have the same volt per turn. Even if there is not direct electrical feedback form the open secondary, there is magnetic feedback that tells the supply about the open secondary power demands. As I said before, the regulation is not going to be as good as when both outputs are regulated but only you know how tight regulation you need for your design. Once you have a prototype running is easy to try to adjust the supply to meet your requirements by implementing some techniques I mention in my previous post.