No abstract

A power management system is a critical component of the system which needs Li-ion battery packs for power supply. This paper proposes a fully integrated, high-precision, and high-reliability Integrated Circuit (IC) for the power management system of Li-ion battery packs. It has full protection circuits including overvoltage, overtemperature, and overcurrent circuits with measuring voltage accuracy of 0.2 mV and a 15-bit internal Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC). This IC is designed to protect the system automatically and measure the battery cells’ voltage, temperature, and charging or discharging current with high precision. It also provides an I2C interface to communicate with an external Microcontroller Unit (MCU), making it achievable to perform battery cells’ voltage balancing and SOC estimation with 0.1% estimation accuracy in an hour.

In this paper, a digital algorithm based on a 15-bit, 5 million samples per second (MSPS), high-speed successive approximation register (SAR) analog-to-digital converter (ADC) is presented. It features on comparator offset cancellation and capacitor mismatch calibration. The algorithm uses a 13-bit bypass array to measure the errors of both comparator and capacitors. During calibration, errors are read and put into the bypass array to compensate for the mismatches of the main array. Verified by MATLAB, the errors of the SAR ADC output can be corrected into 1 LSB with the help of calibration. The simulation results show that the proposed algorithm improves the precision of the SAR ADC significantly.