The chip used on this module might do it for you, or just use the entire module: http://www.ebay.com/itm/DC-DC-Boost-Buck-Converter-Step-Up-S= tep-Down-Supply-Module-3-35V-to-2-2-30V-F5-/291360234917?pt=3DLH_DefaultDom= ain_2&hash=3Ditem43d66c5da5 On 4/17/15, Dwayne Reid wrote: > I have a DeWalt battery adapter that takes either a 12V or 20V LiIon > battery input and delivers both 5V USB power as well as 12 Vdc > out. I haven't fully reverse-engineered it yet but the 12V output > uses a TI TPS40200 controller driving a P-channel MOSFET in a SEPIC > configuration using a tiny 33uH dual inductor. It seems to work > really quite well. > > The TPS40200 is relatively inexpensive and is easy to work with - > 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 > part online, it's pretty easy to adapt the standard app note for the > chip into a SEPIC design. All you need to do is add the coupled > inductor and the coupling capacitors. The voltage feedback stuff > stays the same. > > I'll eventually get around to documenting what DeWalt did in their > 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 > 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 t= o >>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 i= n >>particular). For running a PIC project off a single li-ion cell. >> >>Any thoughts greatly appreciated >>Lee > > > -- > 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 > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 Tobias Gogolin Tel. D1 (49) 0151 5187 5210 Tel. D2 (49) 0152 0839 5060 skype: moontogo You develop Sustainable Ranch Technology at http://tech.groups.yahoo.com/group/SURA-TECH an Open Source Electric Motor/Alternator at http://groups.yahoo.com/group/Performance_Axial_Flux and an Open Source Motor Controller at http://groups.yahoo.com/group/GoBox --=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 .