A 12-Cell Battery Monitor IC with 2-Channel 16-bit ADCs and Isolated Bidirectional Data Interface

A 12-cell batter monitor IC is presented for the battery management system of electric vehicles. To achieve fast and precise measurement, two 16-bit $\Delta-\Sigma$ ADCs are used in parallel for all the 12 battery cells, which are divided into 2 groups controlled by 2 separate high-voltage multiplexers. Two transformer-based data interfaces are designed to enable isolated bidirectional data transmission to a low-voltage MCU. Fabricated in a $0.18-\mu \mathrm{m}$ BCD process, measurement results with a 3.3-MHz on-chip clock show that all the 12 battery cell voltages can be measured in 1 ms with error less than 1 mV. The chip consumes 20.5 mA when it is in operation.