Re: S.s. MOSFET-driving

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jan Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>

Hi,

> There's been mention made recently of the IR2110-series ICs for driving
> Tesla-coil MOSFETs.  A long while back I had intractable trouble using those
> ICs, seemingly because the very high-impedance voltage-translating circuitry
> within the IC was being affected by the coil's electric field. 

IR2110 etc do suffer from Vs undershoot and bootstrap capacitor
overcharging (=> stuff blows up) if you don't do all of the tricks
mentioned in the data sheet and corresponding application notes.

It should be A LOT easier to just forget that bootstrap scheme, i.e.
leave out that fast diode. Use a completely separate small 15VDC power
supply for the IR2110 floating channel instead. A negative bias
circuit would be very handy too, one is somewhere in the application
notes afaik.

By the way, for 0%-90% duty and negative bias via a gate drive
transformer I saw a schematic somewhere with just two schottkys, two
caps, and a bleeder resistor - this is cheaper than the two-mosfet
setup. Haven't had time to try it out yet, but if you are interested,
I have the schematic as a PDF file.

 - Jan
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