2EDN mosfet driver burns out when connected to PWM signal
A opto-coupler here makes no sense since you are using a common ground on both sides anyway.

Are you really sure that 12 V is a valid input to the FET gate driver?  You didn't link to the datasheet, so I didn't check.

Gate drivers need good bypassing.  You don't have any bypass cap at all.  Doesn't the datasheet even point this out?  Most do.



Connect the digital output directly to the gate driver input.  Disconnect the output of the gate driver and verify everything is operating as it should.  This include checking the power supply during switching.

If you previously abused the gate driver, toss it, get a new one, and be more careful in the future.