DC2069A: 14.2V @ 16.6A, 17 ~ 54 Vin, Solar Battery Charger

Demonstration circuit 2069A features LT®8490, a high performance buck-boost converter that implements an MPPT function and flexible charging profiles suitable for most battery types such as flooded and sealed lead acid batteries and Lithium-Ion batteries, and can operate from input voltages above, below or equal to the battery voltage.

The demo board is configured for a 17V to 54V input voltage range and the power source can be a solar panel with 36 to 72 cells (up to 200W) or a DC voltage source. Two input connectors are provided. An LTC4359 ideal diode controller protects the DC power supply output from being back fed from the solar panel. This allows, for example, that a 24VDC supply is plugged in while a solar panel with higher voltage is being used to power the circuit.

On-chip logic provides automatic true power point tracking for solar powered applications. The MPPT function not only continuously tracks the maximum power point, it is able to select the correct maximum on the power curve to increase power harvested from the panel during partial shade conditions, when multiple peaks occur on the power curve. During periods of low light, a low power mode allows the charger to deliver a small charge current even if there is not enough light for the MPPT function to operate.

The demo board output is set up for charging a 12V SLA battery with up to 16.6A charge current. Two charge configuration headers are provided so the user can select different charge algorithms.

There are two onboard LEDs that display information on the charge stage, and they will blink fault messages if the charger shuts down because of a fault. A simple serial interface also sends out status bytes that can be interpreted by external circuitry.

An RJ25 modular jack can be used to connect an external NTC temperature sensor mounted at the battery. This allows temperature compensation of the charge voltage, which is important for lead acid batteries. The same connector can be used for remote sensing of battery voltage, to compensate for voltage drops in long battery cables.

The LT8490 data sheet gives a complete description of the device, operation and application information. The data sheet must be read in conjunction with this demo manual for DC2069A. The LT8490EUKJ is assembled in a 64-lead (7mm × 11mm) plastic QFN package with a thermal pad underneath the chip. Proper board layout is essential for maximum thermal performance.