A multi-cell battery pack monitoring chip based on 0.35-μm BCD technology for electric vehicles

Abstract

This letter presents a multi-cell battery pack monitoring chip for electric vehicles (EVs). A multiplexer based on p- and n-type lateral double-diffused MOS (LDMOS) transistors is proposed to select the battery voltage in a battery pack with up to 12 series-connected battery cells. Measuring of the cell voltages is realized by a 12-bit incremental ΣΔ analog-to-digital converter (ADC) with offset cancellation. Fabricated in a 0.35-μm Bipolar-CMOS-DMOS (BCD) technology, measurement results show that an absolute conversion error of less than 3 mV is obtained. The conversion time for each cell is less than 600 μs under a 1-MHz clock signal generated by an internal oscillator. The chip area is 4×3.8 mm² and the current consumption is 510 μA in measuring mode, resulting in a operation power loss of 25.5 mW under a 50-V power supply.