This device is a synchronous buck-boost battery charge controller, offering a low component count, high efficiency solution for space constrained, 1s-5s battery charging applications.
The BQ25731 charges a battery from a wide range of input sources including USB adapter, high voltage USB PD sources, and traditional adapters.
During power up, the charger sets the converter to a buck, boost, or buck-boost configuration based on the input source and battery conditions. The charger automatically transits among the buck, boost, and buck-boost configuration without host control.
In the absence of an input source, the BQ25731 supports a USB On-the-Go (OTG) function from a 1- to 5-cell battery to generate an adjustable 3 V to 24 V on VBUS with 8-mV resolution. The OTG output voltage transition slew rate can be configurable, which complies with the USB PD 3.0 PPS specifications.
The BQ25731 monitors adapter current, battery current, and system power. No additional BATFET is needed, when a depleted battery is inserted charge is enabled by default for 256 mA.