Can TOP-HX can be used for led lighting application just as top-gx, if we cant use what the reason,,
For LED Lighting applications, please consider LinkSwitch-PL or LinkSwitch-PH family. These devices are created specifically to cater for LED applications. There are lots of Reference Designs and Design Example Reports that are available in Power Integrations website to help you on your design.
TOP-HX is not optimized to be used for LED applications.