Novel broken line detection circuit for multi-cells Li-ion battery protection ICs

Abstract

To reduce the excessive power consumption and eliminate the battery voltage imbalance caused in conventional method, a novel broken line detection scheme for Li-ion battery protection integrated circuits (ICs) is presented in this study. The main part of the proposed circuit consists of pull-up, pull-down current source, source-driven MOS, a control switch and a bias current source. A narrow pulse control signal is adopted to trigger broken line detection periodically so as to suppress the detection current consumption, while the disadvantage of battery voltage imbalance is overcome. The proposed circuit has been implemented in a seven cells Li-ion battery protection IC with 0.18 µm 45 V bipolar-CMOS-DMOS process successfully. The experimental results confirm that the chip can reliably detect the disconnections of Li-ion batteries and take protective measures in a wide cell voltage range from 2.2 to 4.2 V. Furthermore, based on the derivation in this study, the proposed technique can significantly reduce the detection current consumption of each cell, which is well beneficial for low power consumption and battery voltage balance.