What I did today is probably not so cool for the electrical engineers here, but for me as a software guy I am pretty proud of my idea.
I have the controller running at 3.3V and 8MHz and needed to drive 3 white LEDs in series for my LCD backlight. Now where to get a cheap driver for this? Here comes my approach:
I use Timer 2 to generate PWM output. This drives a PDTD113Z (basically an NPN transistor with 2 integrated resistors). This driver in turn switches a 330uH inductor in a configuration like so http://upload.wikimedia.org/wikipedia/commons/3/39/Boost_conventions.svg.
Works like a charm. I am very happy. I did not yet find the time to control the wave form with the scope. But at least it works and was simple to setup :)
Initially I intended to use a FET but then learned that the FET appears as a capacitor for the AVR output and might damage it. Althoug I now have a satisfactory solution: is this concern justified?
That is what would have been a really good choice? FET, FET + Gate resistor, or NPN driver (as I choose)?