BQ2407x series devices are integrated lithium-ion linear chargers and system power path management devices, which are suitable for portable applications with limited space. This kind of device runs through USB port or AC adapter, and can support charging current up to 1.5A. They have input voltage protection function in the input voltage range, so they support unregulated adapters. The USB input current limiting accuracy and startup sequence of BQ2407x enable this device to meet the USB-IF surge current specification. In addition, input dynamic power management (VIN-DPM) can prevent the charger from damaging the misconfigured USB power supply.

BQ2407x has dynamic power path management (DPPM), which can independently charge the battery while supplying power to the system. When the input current limit causes the system output to drop to the DPPM threshold, the DPPM circuit will reduce the charging current; Therefore, the charging current can be monitored at any time when supplying power to the system load. This feature reduces the number of charging and discharging cycles on the battery, which can realize the normal termination of charging and enable the system to operate under the condition of being powered by a defective or incomplete battery pack.

In addition, this series of chargers can provide regulated system input, and even when the battery is completely discharged, the system can be turned on instantly after being connected to the power supply. When the adapter cannot provide peak system current, the power path management architecture also allows the battery to meet the system current requirements, so a smaller adapter can be used.

The battery charging process is divided into three stages: pre-charging, constant current charging and constant voltage charging. During all charging stages, an internal control loop monitors the IC junction temperature and reduces the charging current if this internal temperature threshold is exceeded. The charger power stage and charging current sensing function are completely integrated. The charger has the functions of high-precision current and voltage adjustment loop, charging status display and charging termination. The input current limit and charging current can be programmed using external resistors.