Figure 1: Charging profile of Li-ion battery
To implement this profile, battery voltage and charging current needs to be known at every time. Besides these, the temperature of the battery also needs to be kept in check. This is required because while charging, the battery tends to get heated. If the temperature exceeds the battery’s specified limit, it can cause damage to the battery.
The user has two options when it comes to battery charger implementation: using a dedicated battery charger IC or a more general-purpose microcontroller. The first option offers a quick solution to the problem but with limited configurability and user interface options (LED indications). Alternatively, the use of a microcontroller will take longer to design but offers configurability options in addition to the potential to integrate other functions such as battery state of charge (SOC) calculation and sending such information over a communication interfaces to the host processor in the system. In addition, a microcontroller is not equipped with the power circuitry necessary for a charger and requires external BJTs or MOSFETs. However, the cost of these power components is lower as compared to the microcontrollers or dedicated charger ICs.