Hi, Im looking at driving an lcd EL backlight, but without the large/noisy transformer, the above chips look quite interesting, but seem unavailable from uk stockists, are there any others that are readily available ?
I thought it would be relativly easy but ive looked at various ways of doing it, the problem seems to be the amount of capacitance, the amount of power they consume is small but the reactive power of this panel is about 3W,
250pf/cm^2 => 35nf on my 1/4 vga panel I used a small RM6 type ferite as a transformer so it resonated at 1khz but it got way too hot, a much larger one would be too big, although I tried a line output transformer and it worked quite well, I tried the aproach of a pulsed dc converter, however the problem is the same - the capacitance requires a considerable current to charge it up is wasted when it is dumped through a discharge transistor, this is much how the above ICs work, they do however offer small size but are only capable of driving small devices eg mobile phones.My next aproach is to drive the panel from a dc source but using the switching transistors in a class D configuration so the reactive energy is recovered as much as possible, if the above ICs could be driven this way it would be a nice solution, driving the class d stage with suitable pulses from the MCU, would be nice if there was a nice 250v+ mosfet hbridge with hi level driver available, IR do a self oscilating one but again seems unavailable.
Whats an easy way to make a low current hi voltage H bridge ? maybe using a pnp or pch for the top device and driving it through a capacitor ?
Im also wondering how the phospour is energised exactly, is it with the "displacement" current ? as I assume it is non conductive.
Colin =^.^=