The BQ25170 is an integrated 800-mA linear charger for 1-cell Li-Ion, Li-Polymer, and LiFePO4 batteries targeted at space-limited portable applications. The device has a single power output that charges the battery. The system load can be placed in parallel with the battery, as long as the average system load does not prevent the battery from charging fully within the safety timer duration. When the system load is placed in parallel with the battery, the charge current is shared between the system and the battery.
The device has three phases for charging a Li-Ion battery: precharge to recover a fully discharged battery, fast-charge constant current to supply the bulk of the charge, and voltage regulation to reach full capacity.
In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold, TREG, is exceeded.
The charger power stage and charge current sense functions are fully integrated. The charger function has high accuracy current and voltage regulation loops, charge status display, and automatic charge termination. The charge voltage and fast charge current are programmable through external resistors. The precharge and termination current threshold track the fast charge current setting.