The LT8490 synchronous buck-boost battery-charging controller for lead-acid and lithium batteries offers automatic maximum power-point tracking (MPPT) and temperature compensation for solar applications. Operating from input voltages above, below or equal to the regulated battery float voltage, the charger’s various selectable constant-current constant voltage (CC-CV) charging profiles suit it for a host of battery chemistry types (e.g., sealed lead acid, gel cells, flooded cells). Onboard charge-termination algorithms eliminate the need for software or firmware. Input voltage ranges from 6 to 80 V, while battery float voltage output ranges from 1.3 to 80 V via a single inductor with four-switch synchronous rectification. Charging currents can reach 10 A depending on the choice of external FETs. The device enables a sweep of a solar panel’s full operating range, finding the true maximum power point—even in the presence of local maxima points caused by partial shading of the panel. Once the maximum power point is found, the controller operates at that point while using a dithering technique to track changes in the local maximum power point. Automatic temperature compensation of battery-charge voltage occurs by sensing an external thermistor on the battery.