2 Hardware Theory of Operation

The system hardware is divided into several sections: voltage monitors, current monitors, the charger, the output regulator and the temperature sensor. The voltage monitors are voltage dividers that scale the measured voltage down to a range the ADC can handle. The current monitors are high-side current mirrors that measure and offset the charge/discharge current down to a range the ADC can measure. The charger handles the constant current/constant voltage charging curve for the 2-cell Lithium Polymer battery pack, and the output regulator converts the battery voltage efficiently down to 5V for the load. The temperature sensor is included to monitor the battery temperature to detect faults and to prevent hold/cold charging/discharging of the battery.