Research on Switched-Capacitor Based Voltage Measurement for Multi-Cell Battery Management Systems

With fast battery technology growing, multi-cell with higher energy densities requires battery management system (BMS) performs with high input voltage. Switched-capacitor architecture can be used in the high-voltage condition and combined well with the successive quantization circuits with given BCD process. However, the typical structure of switch for high-voltage sensing has some limitation to switched-capacitor measurement architecture. A modified sensing structure based on gate cross-coupled bootstrap circuit is proposed in this paper. The performance of proposed structure is simulated with 0.18um 70V BCD process at the temperature range of -40°C~125°C and process corner of TT, FF, SS, FS, SF. The simulation results show that at the high common input voltage, the measurement error is no more than 1mV.