bq25731 Buck-Boost Battery Charge Controller Texas Instruments bq25731 Buck-Boost Battery Charge Controller is a synchronous buck-boost battery charge controller. It can be used to charge a 1- to 5-cell battery from a wide range of input sources, including a USB adapter, high voltage USB-C Power Delivery (PD) sources, and traditional adapters. It offers a low component count, high-efficiency solution for space-constrained, 1- to 5-cell battery charging applications. 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 seamlessly transits between the buck, boost, and buck-boost operation modes without host control.