Texas Instruments BQ25792 Switch Mode Step-down Boost Charger
The Texas Instruments BQ25792 switch mode step-down boost charger is a fully integrated switch mode step-down boost charger suitable for 1 to 4 lithium-ion batteries and lithium-polymer batteries. In order to achieve a compact design and minimize the number of components, the charger integrates four switch MOSFETs (Q1, Q2, Q3, Q4), input and charging current detection circuits, battery FETs (BATFET), and all loop compensations for step-down and step-up converters. It provides high power density and design flexibility, and can be used on USB Type-C ™  Charge the battery within the entire input voltage range of USB-PD applications such as smartphones, tablets, and other portable devices.
The charger supports narrow VDC (NVDC) power path management, where the system regulation voltage is slightly higher than the battery voltage, but not lower than the minimum system voltage. Even if the battery is completely discharged or removed, the system can continue to operate. When the load power exceeds the rated value of the input power supply, the battery enters replenishment mode to prevent input power overload and system collapse.
These devices charge batteries from various input sources, including traditional USB adapters, high-voltage USB-PD adapters, and traditional bucket adapters. The charger can seamlessly switch between step-down, step-up, or step-down step-up configurations based on input voltage and battery voltage, without the need for host control. The optional dual input source selector manages power from two different input sources. The host controls the input source selection 2C through I and prioritizes the first available input source.
The BQ25792 switch mode step-down boost charger provides various safety features for battery charging and system operation, including battery temperature negative thermistor (NTC) monitoring, trickle charging, pre charging, and fast charging timers, as well as overvoltage/overcurrent protection on the power input pins of the battery and charger. When the chip temperature exceeds the programmable threshold, thermal regulation will reduce the charging current. The STAT output of the device reports the charging status and any fault conditions. When a malfunction occurs, the INT pin will immediately notify the host.
These devices also provide a 16 bit analog-to-digital converter (ADC) for monitoring charging current and input/battery/system voltage, TS pin voltage, and chip temperature. These devices are packaged in a WCSP 2.9mm x 3.3mm 56 pin package.