The second proposed MPPT solution is a combination of the FOCV and P&O methods and leverages several key features of the BQ25798. First, the charger implements a simple yet robust MPPT feature using the VINPDM feature of the part with a configurable K-factor. Second, the charger allows access to the charge current via the ADC to monitor if the MPP has been reached.

Figure 2-4 shows a demonstration of this MPPT algorithm. First, the user starts with MPPT enabled at the lowest setting of 56.25% of the open circuit voltage. Every 30 seconds, the MPPT register setting is increased and the change in the charge current is observed. After increasing the MPPT register setting to 87.5% it was noticed the charge current decreased, indicating the 81.25% maximizes the charge current. The host could rerun the algorithm as the sun condition changes to find the new MPPT.