Battery charger, help needed please

Discussion in 'The Projects Forum' started by PatBateman, Jun 7, 2008.

  1. PatBateman

    Thread Starter New Member

    Jun 7, 2008
    2
    0
    Hi, i am currently building a smart charger circuit for a 12v lead acid car battery. i am using the uc3906 chip from the site (http://focus.ti.com/lit/ds/symlink/uc3906.pdf)

    It may sound like a silly question but the resistor contained in the circuit `Rt' is it actually a resistor i require or is it simply a term for the total resistance of the circuit. I have used the design procedure to work out all the other values of components but am not totally sure about the Rt. Any feedback/ information would be greatly recieved as i am working to a deadline. Thanks
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Rt is a resistor. The formula shows how to derive E and I for the relationship R = E/I. It looks like application note 104 would be very useful.
     
  3. PatBateman

    Thread Starter New Member

    Jun 7, 2008
    2
    0
    Thanks the not 104 did contain lots of useful information. However i didnt notice any info on Rt or the formula.
    From the design procedure i worked out previously :

    RT=(V IN-VT-2.5v) / IT
    RT= 260

    I am not sure how accurate this is?
     
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