The LM3621 is a full function constant voltage, constant current (CVCC) lithium-ion (Li+) battery charger controller. It provides 1% regulation accuracy over the specified temperature range without requiring the use of external precision resistors. The IC controls five charge modes: conditioning, fast, top-off, monitor and maintenance. In addition, the LM3621 detects and flags defective batteries as well as over current and over voltage fault events. The architecture of the IC is based on high gain constant voltage and constant current control loops. The LM3621 is designed to control a switching charger, a linear charger or an off-line ac adapter charger. The LM3621 consists of a logic controller, precision bandgap reference, wide bandwidth transconductance error amplifiers, comparators, and an output buffer. The LM3621 is available in a 16-pin SOIC package and is specified over the range of 0C to 70C.