I've searched, lurked, and read tons of information on getting 5V from battery as long as you only need ~500mA or less. I need up to 6A though and just can't find anything like this. I'm not a very strong hardware guy and I'm running out of keywords to search and need some real practical usage info to point me in the right direction.
2) 2-3A typical (theoretical max of 6A)
3) Circuit (not including cells) must
fit inside 5/8" inner diameter tubing (no really big components)
4) Descending order of importance: Size, Efficiency, Simplicity, Weight, Cost
5) Circuit will be somewhat confined and cannot generate a huge amount of heat
6) Li-ion preferred (even with the hassles of charging and protection) but am open to information here if this is an issue
Questions (given the requirements above):
1) Is it more efficient to use under-voltage pack (e.g. 3.6v) and boost or over-voltage (e.g. 7.2V) and regulate/buck?
2) Where should I start? Buck converter, switching regulator, linear voltage reg, something else? I believe I've generally listed them from best to worst but don't understand which works best given my requirements above (especially size?).
3) Can someone point me to a reference design, IC, etc somewhere for this kind of high current usage? I can't safely build this circuit without something
to work from.
Here is an example of a perfect circuit... except I need up to 6A (and this, like most others, max at 600mA):http://www.sparkfun.com/products/10255