I missed the bit about it being redesigned! Possibly not a good choice then= .. Matt On 29 May 2013 23:46, "RussellMc" wrote: > On 30 May 2013 00:57, Matt Callow wrote: > > > This plus an LDO may do the job. > > > > http://www.adafruit.com/products/390 > > > > (Although it's currently out of stock) > > > > That cct is notionally ideal for solar use as it can implement a form of > near MPPT tracking. by holding the panel at a deemed-optimum voltage. > > HOWEVER as they are using a linear panel load and not a smps this is a > dream. > > That uses an MCP73871, which is in stock at Digikey. > Datasheet - http://ww1.microchip.com/downloads/en/DeviceDoc/22090b.pdf > Their circuit diagram - > > https://github.com/adafruit/USB-DC-Solar-Lithium-Ion-Polymer-charger/blob= /master/schem.png > > The "special magic" is in R2 & R3 which divide Vin and load it down until > it puts 1.23V on the VPCC pin. > In this case that sets Vin to 4.55V which they deem to be the optimum for > quasi MPPT tracking. > > Note that they say that > > 1. They have spent a lot of time fiddling to get this circuit "just > right": > > 2. It is now unavailable as they are redesigning it > > :-) > > Caveat Emptor maybe. > > > Russell > -- > 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 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .