Hi,
I am currently doing a project where I’m developing a LiFePO4 battery charger to charge 4 of these cells in series. I am using the bq2954 IC and the circuit that I have implemented is found in the “Using BQ2954” application notes as follows:
http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slua447&fileType=pdf
The calculations for the above circuit are done using the formulas in the “bq2954 Datasheet” as follows:
As can be seen from the ‘datasheet’ of the bq2954 IC, the Charge Current (Icharge), to charge the battery pack (4 cells in series, in this case), is determined by the Rsns (Current Sense Resistor). Thus, using the formula “Rsns = Vsns/Icharge” which comes to “Rsns = 0.25V/Icharge”, I set my charging current (Icharge) as 5A, so the Rsns value comes to 50 mohms.
However, the problem that I am facing is that even with this value of Rsns, I cannot get my Icharge as 5A. It is only showing as arnd 200mA, which causes the charging to take place, but very slowly.
Could someone please help me out? How can I solve this problem and increase my Charge Current (Icharge) ?
Thanks a lot! :]