A high-precision voltage sampling circuit for 14-series lithium-ion batteries utilizing an improved resistive level shifting technique

Abstract

In order to promote a low-carbon lifestyle, more and more electric bicycles are being put on the market. High-precision battery voltage sampling plays a vital role in the safe and reliable operation of electric bicycles. Based on improving the traditional resistive level shift circuit, this paper proposes a high-precision voltage sampling circuit for 14-series lithium battery packs. Voltage sampling is carried out by combining a High-Voltage Multiplexer (HV MUX) and a multiplexed resistive level shift circuit, and the current compensation circuit is designed to solve the problem of channel leakage current in the gate drive circuit when p-type and n-type Laterally Diffused Metal–Oxide–Semiconductor (LDMOS) are used as high-voltage switches. In addition, the influence of leakage current in the level shift circuit on battery voltage consistency and sampling accuracy is eliminated through the adaptive current compensation circuit, and the influence of operational amplifier mismatch on sampling accuracy is eliminated through chopper stabilization technique. Verify circuit performance based on 0.35$\mu$m Bipolar-CMOS-DMOS (BCD) process, The results show that the maximum channel leakage current of HV MUX is 18.75nA, under the standard conditions of TT process angle and 27 °C, the maximum measurement error of the voltage sampling circuit is ±1.4 mV. Under comprehensive PVT verification, the maximum measurement error is 2.2 mV.