Intelligent Lithium Battery Charging Management System
In project development, we may encounter issues where the circuit fails to turn on and the battery fails to charge, even with an LED. To address this problem, this article will introduce a design for a battery charger with load sharing functionality to ensure correct battery charging and normal operation of the main circuit.
We will utilize Microchip’s popular charging IC, MCP73831/2, suitable for single-cell lithium polymer and lithium-ion batteries, with a maximum charging current of 500mA. Additionally, we will reference Microchip’s application note AN1149 for load sharing design to ensure the charger’s stability and reliability.
Charging Issues without Load Sharing
During the pre-charge and constant current charging stages, the charging IC’s current limit may cause insufficient battery charging. If the load’s current demand exceeds the charging IC’s limit, the battery will be forced to discharge instead of charging. For example, if the charging IC’s current limit is 40mA and the load requires 50mA, the battery will discharge by 10mA.
During the constant voltage charging stage, the charger typically waits until…