Perhaps if you post a valid link somebody will respond. Em 12/9/2011 09:40, V G escreveu: > On Mon, Sep 5, 2011 at 7:27 AM, V G wrote: > >> Circuit (click to enlarge) >> >> [image: cc.png] >> http://solarwind.byethost7.com/cc.png >> >> >> I designed this Li-ion charging circuit so I could select my own maximum >> charge voltage (so I could get a better service life out of the cell by >> charging it up to only 4.0V or less). At the same time, I can fine tune = the >> maximum charge current. This method (constant voltage with current limit= ) >> models (as far as I know) the normal method for charging Li-ion (constan= t >> current until a certain voltage is reached, then switch to a constant >> voltage). >> >> I would like some suggestions for it as I'm pretty sure there are a few >> things to improve. >> >> * The chip in the middle is a high side current sense amplifier. >> * The voltage source on the left is my best attempt at modelling a Li-io= n >> battery. It gains voltage as it's being "charged" (DC operating point >> stepped to increase voltage). >> >> * Graph: >> ** cyan: power dissipated by the MOSFET >> ** blue: current through r_sense and the battery >> ** red: MOSFET gate voltage >> ** green: voltage across the "battery" >> >> >> Questions: >> >> * I placed C2 (next to the MOSFET) to smooth out the gate voltage and gi= ve >> a more "analog" signal so the MOSFET can control the current better. >> Thoughts about this? >> * I chose a MOSFET instead of a BJT so I can get the full 4.0V out of th= e >> charging voltage source. Thoughts? >> * What are your general opinions about this circuit? Could anything be d= one >> better? Is the whole concept here stupid to begin with? >> * Is C1 (above the opamp) too large a value? I was suggested a value of >> around 50pF a while ago while designing using a similar circuit block, f= or >> opamp voltage output stability. Note that there's also C2 (beside the >> MOSFET) as well, which I believe serves the same purpose. >> > > Anyone? :( --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .