The bq2423x series of devices are highly integrated Li-ion linear chargers and system power-path management devices targeted at space-limited portable applications. The devices operate from either a USB port or ac adapter and support charge currents between 25 mA and 500 mA. The high-input-voltage range with input overvoltage protection supports low-cost, unregulated adapters. The USB input current limit accuracy and start-up sequence allow the bq2423x to meet USB-IF inrush current specification. Additionally, the input dynamic power management (VIN–DPM) prevents the charger from crashing poorly designed or incorrectly configured USB sources.
The bq2423x features dynamic power-path management (DPPM) that powers the system while simultaneously and independently charging the battery. The DPPM circuit reduces the charge current when the input current limit causes the system output to fall to the DPPM threshold, thus supplying the system load at all times while monitoring the charge current separately. This feature reduces the number of charge and discharge cycles on the battery, allows for proper charge termination, and enables the system to run with a defective or absent battery pack. Additionally, this enables instant system turn-on even with a totally discharged battery. The power-path management architecture also permits the battery to supplement the system current requirements when the adapter cannot deliver the peak system currents, enabling the use of a smaller adapter.
The battery is charged in three phases: conditioning, constant current, and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if the internal temperature threshold is exceeded.
The charger power stage and charge current sense functions are fully integrated. The charger function has high-accuracy current and voltage regulation loops, charge status display, and charge termination. The input current limit and charge current are programmable using external resistors.
Fully Compliant USB Charger
Selectable 100-mA and 500-mA Maximum Input Current
100-mA Maximum Current Limit Ensures Compliance to USB-IF Standard
Input-based Dynamic Power Management (VIN– DPM) for Protection Against Poor USB Sources
28-V Input Rating With Overvoltage Protection
Integrated Dynamic Power-Path Management (DPPM) Function Simultaneously and Independently Powers the System and Charges the Battery
Supports up to 500-mA Charge Current With Current Monitoring Output (ISET)
Programmable Input Current Limit up to 500 mA for Wall Adapters
Programmable Termination Current (bq24232)
Programmable Precharge and Fast-Charge Safety Timers
Reverse Current, Short-Circuit, and Thermal Protection
NTC Thermistor Input
Proprietary Start-Up Sequence Limits Inrush Current