3 Software Theory of Operation

The control software for the battery manager is a software state machine with four states of operation: Idle, Error, Charging and System-On.

The system will operate on one of three modes: Charging, Active Load and Idle. In Charging mode, the system will enable the charger ASIC and monitor its operation via the status line, the supply voltage to the charger, the battery voltage and the battery temperature. The charge current will also be tracked to estimate the current capacity of the battery.

In Active Load mode, the system will enable the switching regulator and monitor load operations via the battery voltage, battery temperature and the load voltage. The battery output current will also be monitored to estimate the remaining current capacity of the battery.

In Idle mode, the system will monitor the battery voltage, battery temperature and charger supply voltage. If the charger supply voltage is enough, the battery voltage is low, and the battery temperature is within the normal range, the system will switch to Charging mode. If the system requests power, and there is sufficient battery voltage, and the battery temperature is within the normal range, the system will switch to Active Load mode.