BQ25172

The BQ25172 is an integrated 800-mA linear charger for 1-cell to 6-cell NiMH batteries targeted at industrial and medical 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 being charged 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 charges NiMH cells in constant current mode only and terminates the charge cycle when the programmable timer expires or the battery voltage exceeds the V_{OUT_OVP} threshold. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold T_REG, is exceeded.

The charger power stage and charge current sense functions are fully integrated. The charger function has high accuracy current, charge status display, and timer-based charge termination. The series cell-count, charge current, and charge timer are programmable through external resistors. Intermittent charging allows a NiMH battery to automatically recharge for a reduced timer duration once its voltage falls below the recharge threshold.