I want to design 3W to 25W dimmable LED driver.
Please suggest me best design or PI IC which can help me and also how i can design it in PI software for verification.
Thanks for considering Power Integrations in your design. As a start, you can go to this site:https://piexpertonline.power.com/
Here, you can create your own designs with the specs that you need. Among the products, use LYTSwitch as these are specialized for Lighting Applications.
You can also visit the Power Integrations website specific for LED Drivers designs:https://led-driver.power.com/
You can explore here and look for reference designs that are close to your application. For example, you may check DER-442 using LYTSwitch-4 which is 30W LED Driver that uses 1-10V Dimming scheme.
Hope this helps.