The BQ25672 is a fully integrated switch-mode buck charger for 1-4 cell Li-ion batteries and Li-polymer batteries. The BQ25672 is also capable of producing a buck-boost, 5V to 12V, output voltage on VBUS when operating in OTG mode. The integration includes the switching MOSFETs, input and charging current sensing circuits, the battery FET (QBAT) and all the loop compensation of the converter. It uses NVDC power path management, regulating the system slightly above the battery voltage without dropping below a configurable minimum system voltage. When system power exceeds the input source rating, battery supplement mode supports the system without overloading the input source.
The charger supports the NVDC power path management, in which the system is regulated at a voltage slightly higher than the battery voltage, but not drop below the minimum system voltage. The system keeps operating even when the battery is completely discharged or removed. When load power exceeds input source rating, the battery gets into supplement mode and prevents the input source from being overloaded and the system from crashing.
The input current optimizer (ICO) allows the detection of maximum power point of an unknown input source.
Besides the I2C host controlled charging mode, this charger also supports autonomous charging mode. After power up, the charging is enabled with default register settings. The device can complete a charging cycle without any software engagements. It detects battery voltage and charges the battery in different phases: trickle charging, pre-charging, constant current (CC) charging and constant voltage (CV) charging. At the end of the charging cycle, the charger automatically terminates when the charge current is below a pre-set limit (termination current) in the constant voltage phase. When the full battery falls below the recharge threshold, the charger will automatically start another charging cycle.
In the absence of input sources, this device supports USB On-the-Go (OTG) functionality by discharging the battery to generate an adjustable, buck-boost, 5-V to 12-V output voltage on VBUS with 10mV step size
The charger provides various safety features for battery charging and system operations, including battery temperature negative thermistor monitoring, trickle charge, pre-charge and fast charge timers and over-voltage/over-current protections on battery and input. The thermal regulation reduces charge current when the junction temperature exceeds a programmable threshold. The STAT output of the device reports the charging status and any fault conditions. The INT pin immediately notifies host when fault occurs.
The device also provides a 16-bit analog-to-digital converter (ADC) for monitoring charge current and input/battery/system (VAC, VBUS, BAT, SYS, TS) voltages.
It is available in a 29-pin 4mm × 4mm QFN package.