DC2069A Analog Devices

DEMO MANUAL DC2069A LT8490 High Efficiency MPPT Battery Charger Controller Description Demonstration circuit 2069A features LT 8490, a high configuration headers are provided so the user can select performance buck-boost converter that implements an different charge algorithms. MPPT function and flexible charging profiles suitable for There are two onboard LEDs that display information on most battery types such as flooded and sealed lead acid the charge stage, and they will blink fault messages if the batteries and Lithium-Ion batteries, and can operate from charger shuts down because of a fault. A simple serial input voltages above, below or equal to the battery voltage. interface also sends out status bytes that can be interpreted The demo board is configured for a 17V to 54V input volt- by external circuitry. age range and the power source can be a solar panel with An RJ25 modular jack can be used to connect an external 36 to 72 cells (up to 200W) or a DC voltage source. Two NTC temperature sensor mounted at the battery. This input connectors are provided. An LTC4359 ideal diode allows temperature compensation of the charge voltage, controller protects the DC power supply output from being which is important for lead acid batteries. The same con- back fed from the solar panel. This allows, for example, nector can be used for remote sensing of battery voltage, that a 24VDC supply is plugged in while a solar panel with to compensate for voltage drops in long battery cables. higher voltage is being used to power the circuit. The LT8490 data sheet gives a complete description of On-chip logic provides automatic true power point tracking the device, operation and application information. The data for solar powered applications. The MPPT function not sheet must be read in conjunction with this demo manual only continuously tracks the maximum power point, it is for DC2069A. The LT8490EUKJ is assembled in a 64-lead able to select the correct maximum on the power curve (7mm 11mm) plastic QFN package with a thermal pad to increase power harvested from the panel during partial underneath the chip. Proper board layout is essential for shade conditions, when multiple peaks occur on the power maximum thermal performance. curve. During periods of low light, a low power mode al- Design files for this circuit board are available at lows the charger to deliver a small charge current even if DISSIPATION (W) DEMO MANUAL DC2069A p erformance s 100 20 18 I OUT 99 18 16 98 16 14 EFFICIENCY 97 14 12 96 12 10 95 10 8 94 8 I IN 6 93 6 DISSIPATION 4 92 4 91 2 2 90 0 0 0 2 4 6 8 10 12 14 16 18 10 15 20 25 30 35 40 45 50 55 CHARGE CURRENT (A) INPUT VOLTAGE (V) DC2069A F01 DC2069A F02 Figure 1. Efficiency as a Function of Charge Current. Figure 2. Input and Output Currents as a Function V = 28V, V = 14.2V of Input Voltage. V = 13.6V IN OUT OUT dc2069afb 2 EFFICIENCY (%) CURRENT (A) ummary