Attached are the Altium Designer project files for a 2-Cell Lithium Ion Charging Circuit. This simple circuit provides a constant 8.4V output with varying current based on the connected battery’s charge state. The circuit uses a LM317T voltage regulator and an LM3420 at its core as the charge controller. The input voltage requires 12 to 20 VDC (recommended 15 VDC). This can be applied via the two pin header provided. The output charging current does not take into account individual cell voltages.
The PCB design is that of a 2 layer board with no ground or power planes. The project files must be opened using Altium Designer.