The XT4052K421MR-G is a Battery Management System-on-Chip (SoC) manufactured by NatLinear. This integrated circuit is designed to provide a complete solution for Li-Ion/Li-Polymer cell battery packs of up to 4 series cells in a SOT-23-5L package. It includes a DC-DC buck converter, current sense amplifier, battery protection functions, low drop-out linear charger, improved charge termination, and sleep modes optimized for low power consumption. The XT4052K421MR-G can be used in applications such as mobile phones, digital cameras, personal media players, and other handheld devices. The part is RoHS (Restriction of Hazardous Substances) compliant and is compatible with a wide range of charge profiles and temperature ranges.