This is the regulator circuit that generates 5 volts for the PIC microcontroller. The 1N4001 diode decouples battery voltage Vbatt from the regulator circuit. The various capacitors provide smoothing and decoupling to provide the microcontroller with a clean stable power supply. A 100n capacitor is connected as close to the PIC supply pins as possible.
The regulator is a TS2950-50 very low dropout 5 volt type which more importantly has very low quiescent current. This regulator consumes about 75 microamps off-load. This helps to keep the current consumption of the whole charge controller to a very low level.
From tests so far carried out, the controller has a current consumption of around 500 microamps (0.5mA).