ISL9221 pdf datasheet (Dual In

The ISL9221 Lithium Ion charging IC is designed to meet the charging requirements of most of today’s handheld devices.The IC provides two inputs for either USB connection where
the current is limited by the USB standard or for
powering/charging from a power adapter.
If the voltage at either VUSB or VDC pin is within the safe
allowable range, the PPR pin is pulled low indicating to the
system processor that external power is available.
Charging can be enabled/disabled by controlling the state of
the EN pin. While charging, the CHG pin is pulled low
indicating the battery is being charged.
The battery is charged to 4.2V with only a 1% error across
the temperature range. USB charge current, Adapter charge
current and charge termination currents can be programmed
via external resistors.
The ISL9221 adds an additional feature in providing a limited amount of current to system architecture while protecting the system from destructively high voltage.