I have a DeWalt battery adapter that takes either a 12V or 20V LiIon=20 battery input and delivers both 5V USB power as well as 12 Vdc=20 out. I haven't fully reverse-engineered it yet but the 12V output=20 uses a TI TPS40200 controller driving a P-channel MOSFET in a SEPIC=20 configuration using a tiny 33uH dual inductor. It seems to work=20 really quite well. The TPS40200 is relatively inexpensive and is easy to work with -=20 it's in a SOIC-8 package. Layout seems to be fairly non-critical. Although I haven't yet found any existing SEPIC designs using that=20 part online, it's pretty easy to adapt the standard app note for the=20 chip into a SEPIC design. All you need to do is add the coupled=20 inductor and the coupling capacitors. The voltage feedback stuff=20 stays the same. I'll eventually get around to documenting what DeWalt did in their=20 unit but this might be enough for you to get started on your own. Note that you aren't stuck with the TI part - many (most?) SMPS=20 controllers can be configured into a SEPIC regulator fairly easily. dwayne At 07:26 PM 4/14/2015, Lee Mulvogue wrote: >G'day all >Any suggestions on some cheap (~$2 max), SIMPLE (SOT, SOIC, MSOP etc) >buck/boosts for 3.3V and 5V? >I've got the TI TPS63001 (3.3V) and TPS63002 (5V), but they are proving to >be a real pain for someone who isn't an electrical engineer! Seems the >PCB layout needs to be extremely specific, but on top of that the actual >physical design is a real pain to work with to ensure no bridging (3x3mm >QFN-10, leads completely under the package). > >Any comparable buck/boosts that are a bit more forgiving in layout and >soldering? Say 300mA+ output, input voltage about 3.0V - 4.3V (5V an >advantage). An enable pin would also be preferable to shut it down (5V in >particular). For running a PIC project off a single li-ion cell. > >Any thoughts greatly appreciated >Lee --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .