IC optimises PV charging up to 80V, handles multiple battery types

November 29, 2013 // By Graham Prophet
An 80V buck-boost lead acid and lithium battery charging controller actively finds the true maximum power point in solar applications

LT8490 is a synchronous buck-boost battery charging controller for lead acid and lithium batteries, featuring automatic maximum power point tracking (MPPT) and temperature compensation. The device operates from input voltages above, below or equal to the regulated battery float voltage.

The LT8490’s full-featured battery charger offers multiple selectable constant-current constant-voltage (CC-CV) charging profiles, suiting it for charging a variety of lithium or lead acid chemistry types, including sealed lead acid, gel cells and flooded cells. All charge termination algorithms are provided onboard, eliminating the need for software or firmware and thus reducing design cycle time.

The LT8490 operates over a wide 6V to 80V input voltage range and can produce a 1.3V to 80V battery float voltage output using a single inductor with 4-switch synchronous rectification. The device is capable of charging currents as high as 10A depending on the choice of external FETs. The LT8490’s MPPT circuit enables a sweep of the full operating range of a solar panel, finding the true maximum power point, even in the presence of local maxima points caused by partial shading of the panel. Once the true maximum power point is found, the LT8490 will operate at that point while using a dithering technique to quickly track changes in the local maximum power point. With this methodology, the LT8490 fully exploits the power generated by a solar panel, even in non ideal operating environments.

The LT8490 performs automatic temperature compensation of the battery charge voltage by sensing an external thermistor on the battery. The STATUS and FAULT pins can be used to drive LED indicator lamps. Charging current limits can be adjusted by changing as few as one or two resistors, and a charging time scale can be selected with the appropriate resistor divider. Other features of the device include: input and charge current limit pins, a 3.3V regulated LDO output, status pins and a synchronisable fixed switching frequency.

The LT8490 is available