A number of people are now making ICs designed to upconvert from a single solar cell. There are advantages in doing so but the very high current for a given power level seems to me to make this more a gimmick than a really useful methiod. Using even say 4 PV cells gets you 2V and a lot more efficincy. Ther 1 x PV input devices seem to achieve under 70% effiiciency which is commendable in the circumstances but poor overall. . Intovation make one. So do Motorolla and I think TI and ST may too. I also recently posted re an IC designed to start at down to about 20 mV (!!!!) to charge a capacitor for eg burst mode radio transmitters etc using energy sources such as thermal peltier etc. Inefficint but clever. Uses an analog oscillator to achieve the vv low operating voltage. Using a single PV cell gives linear degradation with shadowed area when cells are shadowed. Cells do not need to be cut other than to fit available space and there is no cell joining or link losses. These seem to be small gains compared to the square law I^2R losses.incurred. eg a 10 Watt 0.5 volt panel up converting to say 5V for eg LiIon cell charging must handle a mean current of 20 A. Not vast - but if resistive losses are to be kept to say 5% then R effective can only be 0.05 x 0.5/20 = 0.00125 ohm. 1 milliohm for tracks connections FET Rdson, and inductor resistance is an immense challenge. True Rdsons of 1 milliohm are exttremely rare. If you get an actual resistive loss all up of say 10 milliohm then losses (mean) are I^2R = 20^2 x 0.010 = 4 Watts or 40% !!!!!!!!!!!! . Despite this Intovation report havin sold about 400,000 cellphones using this system for in-phone PV panels. It seems to me to be a triumph of marketing and flash technology over performance. Not to mention what happens when you leave your phone in the rasin - or want to charge it and use it at the same time. Note that the prior 20A is mean cutrrent - a boost converter will peak at above that during on cycle and losses will be even higher. Russell McMahon On 18 February 2010 02:44, Alan B. Pearce wrote: > >It's designed for 1.8-5.5 Vin operation but will start on 0.8V in. > > > I have seen a chip recently that claimed to start on 0.65V IIRC. Also > apparently Microchip have a similar boost converter that is due to be > announced imminently. > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist