I am using a UC1845A to control the switching element MOSFET (FCB20N60F) which is used for a typical Flyback Converter circuit. MOSFET's drain is connected to transformer. Rarely MOSFET is not working stable and broke down. It is usually works fine. Do you have a suggestion to overcome this FET problem? Can changing the MOSFET to TI csd19502q5b solve the problem (This FET has lower Vds voltage as 80 V although the one used on circuit has 600 V Vds voltage. Can you suggest a better FET instead of FCB20N60F)?