synchronous buck problem

hi everyone..
i did post a lot here regarding the same project. synchronous buck converter for LED driver. initially, the circuit provided very good results.
but after a long time of testing and trying to change this and that every now and then, the buck converter now won't work. both the IGBT's signal seems to be overlapping and the IGBT heats up causing the circuit to fail.
i wonder why is this happening..

so, i'm left with 2 choices.
1. to go for the conventional buck converter. i did try this one, but the results seems weird because the diode wasn't really functioning. but i could step the voltage down just by changing the cuty cycle.

2. add a dead time to one of the signal. i'm using a TL 494 to two optocouplers. but i don't know how. the reason is, i made 2 pcb boards, one for the signal and one for the buck. is there any way to add dead time after the signal goes out from the opto? or do i need to make a new board?

please advice.
thanks

You can increase the dead time by putting up to a 3.3 volts on the dead time control pin 4. Only you can decide if you need a new board. All you need is a couple of resistors and a couple of jumper wires. Is there no room for this on your board? Maybe glue a little board on the side.

twister said:

You can increase the dead time by putting up to a 3.3 volts on the dead time control pin 4. Only you can decide if you need a new board. All you need is a couple of resistors and a couple of jumper wires. Is there no room for this on your board? Maybe glue a little board on the side.

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i can? pin 4 of tl 494 right? what should i do next?
i'm pulling a signal from tl 494 at the same pin (pin 9). one signal goes to 7404 to be inverted. now i know that's not a very good idea. lol.