Re: Flashlight build (In progress)
Ive made a couple of buck and boost converters before, mostly boost however as I needed to deal with a higher voltage and lower current requirements.
Even with a good design, you still need to deal with conduction and switching losses.. and sadly, that means heatsinking. so Do expect a large well sinked driver if you want to push current out of it, however be glad that buck/boost topologies do not generate as much heat as the linear option. (turned to either current or voltage rather then wasted as heat)
I did design a driver for my 100W LED module, and it works fairly well. Here is the schematic of it:
Works fairly nicly for those kind of situations, the driver also has a low voltage cut-off, however it needs to be tuned to be appropriate for the battery (I just usually set the referance to cut off at 11.5V or so, just to keep my lead acids happy, I used an Op-amp set up as comparator, so a regular comparator like the LM311 series will work). Needs a bit of play to work properly, but does do nicly.
Im still working on a synchronous buck-only converter to be able to very high current for my other projects, however it is still in the design stages. When I get it working and tuned out, I suppose Ill post a build thread/schematic of it.
It would be nice if there was some IC to do the feedback and clock for you, but have the IC stand alone and seperate for the switching system, so you are not cripled by the weak internal switch.
Most of texas instruments ICs are like this, and thus can only be used 1V-6V or so at maybe 4A maximum... not that usefull for myself. You can try experimenting with some PWM drivers like the TL494, and some of the UC series from TI.. but I personally haven't done much with those ICs related to buck/boost applications.
TBH, I don't raelly feel like messing with buck/boost drivers, I really like either a buck-only or boost-only system. Just adds to the simplicity of design IMO.
More or less what im trying to say, try to go DIY if you can't find a suitable pre-made driver.