Need External DC-DC for Li-Ion Charge Controller?

Discussion in 'General Electronics Chat' started by johnyradio, Dec 15, 2013.

  1. johnyradio

    Thread Starter Member

    Oct 26, 2012
    39
    1
    Hello

    I'm writing about this chip:
    http://www.sii-ic.com/en/semicon/da...ic/lithium-ion-battery-protection-ic/s-8254a/

    Will this chip step down my power supply to 16.8 volts for charging 4 cells? Or must i also provide an external DC-DC converter?

    My friend tells me i cannot power this chip with a wallwart, if the wallwart voltage exceeds 4.2 volts * number of cells.

    Eg, if i'm charging 4 cells, i must provide a power supply of 4.2 * 4 = 16.8 supply voltage. He says I must use a DC-DC converter if my wall wart exceeds 16.8 volts.

    This confuses me, because the chip says it can accept an operating voltage up to 24 volts. Can i charge 3 or 4 cells directly from a 24 volt wall wart, without an external DC-DC converter?

    thanks

    posted here too
    http://www.dutchforce.com/~eforum/index.php?act=ST&f=24&t=41889
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,969
    744
    As the datasheet says it will take upto 26V DC, so supply it with that.
     
  3. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    Your friend is simply mistaken. The whole purpose of this chip is to allow a wide range of input voltage to be used properly on Lithium batteries.
     
Loading...