Hello,

Thanks for your replies, I have tried both the possibilities, with or without opto isolator.

please see the following circuit diagrams. The ARM_PIN and STAT_PIN are MCU io pins. ARM_PIN output PWM signal from 100Hz to 800Hz user selectable from dip switches.

Please also have a look at power supply circuit.





driving direct from MCU to MOSFET with high current/voltage buffer


driving via opto coupler

When I drove via opto coupler, I attached an 100W light bulb (resistive load) the circuit worked for few minutes, after that MOSFET became shorted between drain and source. The MOSFET got permenantly damaged.

Any more ideas,

BR

Rauf