The bq6400 Battery Management Controller is a complete Li-Ion control, monitoring, and safety solution designed for notebook computers and portable equipment. It is designed specifically to provide an enhanced, optimized solution for packs using three or four series cells. The bq6400 provides accurate gas gauging while providing control, communications and safety functions for the system. It provides simultaneous, synchronized voltage and temperature measurements using one A/D per-cell technology. Voltage measurements are also simultaneous with pack current measurements, eliminating system induced noise from measurements. This allows the precise, continuous, real-time calculation of cell impedance under all operating conditions, even during widely fluctuating loads.