Hello,
I am using LM3658SDX to charge LI-Ion battery 500mAh. I am really puzzled with the charging profile. I am using CH_IN (the rating on the supply is 5V output 500mA) and Rset is 5.6K (I am charging at 2500/5.6K = 446mA). I am monitoring the battery current (using DMM) and the battery voltage.
I connect a fully discharged battery the current goes to 440mA and the battery voltage ramps really quickly to about 3.8 @ 440mA in the first few minutes (exhibiting a true CC characteristic of a LI-ion charging circuit) however the current started to drop noticeably @arounf 170mA as the battery voltage increasing sol slowly. I would expect to see the battery voltage contuinue rising to 4.2V +/- 50mA at a CC (440mA) then the current starts to decrease getting in CV mode. It takes about a total of 3 hours to fully charge it. Could you please possibly help me trying to understand why it exhibits such behavior and why the battery voltage never reaches 4.2@440mA?
Many thanks,
Injy