The ISL6251, ISL6251A is a highly integrated battery charger
controller for Li-Ion/Li-Ion polymer batteries and NiMH
batteries. High efficiency is achieved by a synchronous buck
topology and the use of a MOSFET, instead of a diode, for
selecting power from the adapter or battery. The low side
MOSFET emulates a diode at light loads to improve the light
load efficiency and prevent system bus boosting.
The constant output voltage can be selected for 2, 3 and 4
series Li-Ion cells with 0.5% accuracy over-temperature. It can
be also programmed between 4.2V+5%/cell and 4.2V-5%/cell
to optimize battery capacity. When supplying the load and
battery charger simultaneously, the input current limit for the
AC adapter is programmable to within 3% accuracy to avoid
overloading the AC adapter, and to allow the system to make
efficient use of available adapter power for charging. It also
has a wide range of programmable charging current. The
ISL6251, ISL6251A provides outputs that are used to monitor
the current drawn from the AC adapter, and monitor for the
presence of an AC adapter. The ISL6251, ISL6251A
automatically transitions from regulating current mode to
regulating voltage mode.
