The BQ24091DGQR is a single-cell Li-Ion or Li-Polymer linear charger from Texas Instruments, designed to draw power from a USB port. The charge current is programmable up to 1 A, which sets the charge-time floor for a typical 1000 mAh to 2000 mAh cell — expect roughly a 1-to-2 hour charge from a depleted state, depending on the programmed current and the thermal management of the PCB. The input supply range extends to 6.45 V max, so the part can tolerate the 5 V nominal from a USB host or adapter with margin for cable drop and transient overvoltage.
Fault protection set — no external supervisor needed
On-chip fault protection covers over-temperature, over-voltage, and short-circuit conditions. The protection is active during both charging and standby.