The bq24165, bq24166 and bq24167 are highly integrated single cell Li-Ion battery charger
and system power path management devices targeted for space-limited, portable applications with
high capacity batteries. The single cell charger has dual inputs which allow operation from either
a USB port or higher power input supply (i.e., AC adapter or wireless charging input) for a
versatile solution. The two inputs are fully isolated from each other and are managed by the
bq24165/166/167 with the IN input having precedence.
The power path management feature allows the bq24165/166/167 to power the system from a
high efficiency DC to DC converter while simultaneously and independently charging the battery. The
charger monitors the battery current at all times and reduces the charge current when the system
load requires current above the input current limit. This allows for proper charge termination and
timer operation. The system voltage is regulated to the battery voltage but will not drop below
3.5V. This minimum system voltage support enables the system to run with a defective or absent
battery pack and enables instant system turn-on even with a totally discharged battery or no
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. This enables the use
of a smaller adapter. The 2.5A input current capability allows for GSM phone calls as soon as the
adapter is plugged in regardless of the battery voltage.
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. Additionally, the
bq24166 and bq24167 offer a voltage-based battery pack thermistor monitoring input (TS) that
monitors battery temperature for safe charging. The TS function for bq24166 is JEITA
compatible.
