Battery charger, help needed please

Thread Starter

PatBateman

Joined Jun 7, 2008
2
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
 

beenthere

Joined Apr 20, 2004
15,819
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.
 

Thread Starter

PatBateman

Joined Jun 7, 2008
2
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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