bq24020 pdf datasheet

The bqTINY-II series are highly integrated and flexible
Li-Ion linear charge and system power management
devices targeted at space limited charger applications.
The bqTINY-II series offer integrated USB-port and
ac-adapter supply management with autonomous
power-source selection, power FET and current
sensor, high-accuracy current and voltage regulation,
charge status, and charge termination, in a single
monolithic device.
The bqTINY-II automatically selects the USB-Port or
the ac-adapter as the power source for the system. In
the USB configuration, the host can select from the two
preset charge rates of 100 mA and 500 mA. In the
ac−adapter configuration an external resistor sets the
magnitude of the system or charge current.
The bqTINY-II charges the battery in three phases:
conditioning, constant current, and constant voltage.
Charge is terminated based on minimum current. An
internal charge timer provides a backup safety for
charge termination. The bqTINY-II automatically restarts
the charge if the battery voltage falls below an
internal threshold. The bqTINY-II automatically enters
sleep mode when both supplies are removed.