The ISL9209C is an integrated circuit (IC) optimized to
provide a redundant safety protection to a Li-ion battery from
failures of a charging system. The IC monitors the input
voltage, the battery voltage, and the charge current. When
any of the three parameters exceeds its limit, the IC turns off
an internal P-Channel MOSFET to remove the power from
the charging system. In addition to the above protected
parameters, the IC also monitors its own internal
temperature and turns off the P-Channel MOSFET when the
temperature exceeds +140°C. Together with the battery
charger IC and the protection module in a battery pack, the
charging system using the ISL9209C has triple-level
protection and is two-fault tolerant.
The IC is designed to turn on the internal PFET slowly to
avoid in-rush current at power-up but will turn off the PFET
quickly when the input is overvoltage in order to remove the
power before any damage occurs. The ISL9209C has a logic
warning output to indicate the fault and an enable input to
allow the system to remove the input power.