Then I switched it off and guess what, it did not turn on again!! When I checked the board I found that pins 4(gate driver) and 5(Vcc) L6566B had shorted out to ground (pin 3) internally. My bad luck? Or is it that the L6566B is one of those quirky chips that ST would like to quietly bury and forget about?
ok but you saw the ncp1217 app note concerning a possible reason for that right?
..I am sure you know you cannot disable CS pin.
There is an overcurrent pin, if layout on their demo board is poor it will be triggered.
If you give me your tsfmr spec, I will simulate it for ou (is it BCM, or const freq)?
I will simulate it with my ltspice model I have for both modes..then I send it here to you
first rule of power electronics, always buffer the gate drive with an emitter follower pair
ok I know what you mean, but it does have a gate driver on it so it shouldn't be needed with good layout...I would put resistor 22k from gate to ground, and a series resistor as said, and also the schottky from gate to ground.
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also, try increase c17 to 100nf or 220nf......then reduce r17 to 10k then 1k
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also, what is full part number of the opto...PC817A...PC817D....the A version has ctr down at 50%, so not much, what is the comp pin current for "full stop"?...remember that you must have ENOUGH IN OPTO TO PROVIDE THAT (sorry for caps)
as before, r16 is too high value...should be 1k or 750r...but remember to downsize r15 so it can carry that and not drop too much volts