BQ25628E

The BQ25628E is a highly-integrated 2-A switch-mode battery charge management and system power path management device for single cell Li-ion and Li-polymer batteries. The solution is highly integrated with built-in current sensing, loop compensation, input reverse-blocking FET (RBFET, Q1), high-side switching FET (HSFET, Q2), low-side switching FET (LSFET, Q3), and battery FET (BATFET, Q4) between system and battery. The device uses narrow VDC power path management, regulating the system slightly above the battery voltage without dropping below a configurable minimum system voltage. The low impedance power path optimizes switch-mode operation efficiency, reduces battery charging time, extends battery life during discharging phase, and the ultra-low 0.15µA ship mode current extends battery shelf life. The I2C serial interface with charging and system settings makes the BQ25628E a truly flexible solution.

The BQ25628E has an ILIM pin to set the default input current limit and TS_BIAS pin for controlled thermistor bias.

The power path management regulates the system slightly above battery voltage but does not drop below the programmable minimum system voltage. With this feature, the system maintains operation even when the battery is completely depleted or removed. When the input current limit or input voltage limit is reached, the power path management automatically reduces the charge current. As the system load continues to increase, the battery starts to discharge until the system power requirement is met. This supplement mode prevents overloading the input source.

The BQ25628E initiates and complete a charging cycle without host control. By sensing the battery voltage, it charges the battery in four different phases: trickle charge, pre-charge, constant current (CC) charge and constant voltage (CV) charge. At the end of the charging cycle, the charger automatically terminates when the charge current is below a preset threshold and the battery voltage is higher than the recharge threshold. Termination is supported for all TS pin temperature zones.

The BQ25628E provides various safety features for battery charging and system operations, including battery negative temperature coefficient thermistor monitoring, charging safety timer and overvoltage and overcurrent protections. The thermal regulation reduces charge current when the junction temperature exceeds the programmable threshold. The STAT output reports the charging status and any fault conditions. Other safety features include battery temperature sensing for charge mode, thermal shutdown and input UVLO and overvoltage protection. The INT output notifies the host when a fault occurs or status changes.

The BQ25628E is available in a 18-pin, 2.5mm × 3.0mm WQFN package.