LTC4425 - I have some questions

Discussion in 'General Electronics Chat' started by pityocamptes, Sep 11, 2012.

  1. pityocamptes

    Thread Starter Member

    Jul 25, 2012

    Ok, so let me get this right. The PROG pin with a resistor at 500 ohms, will have a max current outout of 2A. Now if it has a max current limit of 3A and my power supply provides 3 amps MAX, could I change the PROG resistor to 333 ohms for 3 Amps max?
    Also, the Vin/PFI/PFI-RET split resistor group should be set at 2.5v, which is the power failure voltage correct? Since SEL = VIN, then the SuperCaps should be charging at High = 2.7 v per cap? Also, since no voltage out divider exists, will the circuit above basically push out Vin = Vout, as long as Vin does not fall below 2.5v and trigger a power failure, super cap backup? Finally, on PFO, what exactly does the 470K resisitor do, and where does this pin attach to? What exactly is the Vio on this pin - does that attach to Vin, or ground, or does this resistor just float, not attached to anything? Thanks!

    Also, where does the current monitor leg go to, how would this be used? A simple current/volt meter?

    My Li-Ion power supply would actually be a non regulated 3.5 volt min - 5 volt max, 3 amp max, dc supply.