I have an 18W isolated design. O/P voltage is 35V and current 500mA. Design is based on PMP 8011. Winding changed to suit o/p requirement. Circuit diagram is attached. Turs ratio of P to S is 7.5. R1 and R2 are 0.25W. Actually, it requires minimum 0.5W. After few hours, R1, R2 , Mosfet and current sense resistors will burn. R1 and R2 are burning due to insufficient wattage. Mosfet used is 2.5A, 800V. Gate resistor is not used. Is that the reason for failure? For inrush current limit, Can I use 0.5W , 3.3 ohm resistor alone or 3.3 ohm resistor in parallel with 2.2mH inductor? What might be the reason for burning?