The BQ25731 is a buck-boost charger controller for cordless power tools, power banks, and other appliances with rechargeable batteries. It provides seamless transition between different converter operation modes (buck, boost, or buck-boost), fast transient response, and high light load efficiency.

The BQ25731 supports a wide range of power sources, including USB-C PD ports, legacy USB ports, traditional AC-DC adapters, and so forth. It takes input voltage from 3.5 V to 26 V and charges a battery of 1 to 5 cells in series. In the absence of an input source, the BQ25731 supports the USB On-the-Go (OTG) function from a 1- to 5-cell battery to generate an adjustable 3 V to 24 V at the USB port with 8-mV resolution.

The BQ25731 features Dynamic Power Management (DPM) to limit input power and avoid AC adapter overloading. During battery charging, as system power increases, charging current is reduced to maintain total input current below adapter rating.

The latest version of the USB-C PD specification includes Fast Role Swap (FRS) to ensure power role swapping occurs in a timely fashion so that the device(s) connected to the dock never experience momentary power loss or glitching. The device integrates FRS with compliance to the USB-C PD specification.

The TI patented switching frequency dithering pattern can significantly reduce EMI noise over the entire conductive EMI frequency range (150 kHz to 30 MHz). Multiple dithering scale options are available to provide flexibility for different applications to simplify EMI noise filter design.

The I²C host controls input current, charge current, and charge voltage registers with high resolution, high accuracy regulation limits.