Lithium ion battery charger circuit (2)

Published:2011/7/14 23:02:00 Author:TaoXi | Keyword: Lithium ion battery, charger circuit | From:SeekIC

The simplest Lithium ion battery charger circuit is as shown in figure 2-9. This charger uses the lithium ion battery charging controller LM3420-8.4, it can charge two series lithium-ion battery groups. When the voltage of the battery group is lower than 8.4V, the output port of LM3420 has no output current, the transistor VT2 cuts off, so the adjustable voltage-regulator tube LM317 outputs the constant current. The rated output current of the LM317 is 1.5A, if you need the larger charging current, you can use LM350 or LM338. In the charging process, the battery voltage rises and it is detected by the output port of LM3420. When the battery voltage is 8.4V, the LM3420 outputs the current to make the VT2 control the output voltage of LM317.



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