A High Precision Voltage Detection Circuit for Multiple Lithium Batteries

In order to meet the demand of high-precision voltage sampling of multiple lithium batteries, a high-precision voltage detection circuit aiming at the safety problems during battery use is proposed in this paper. The reference voltage generates a high-precision threshold voltage through the resistor divider network, and the sampling voltage is improved by using the principle of capacitance divider. The circuit uses time-division multiplexing to achieve voltage detection function, a comparator detects multiple threshold voltages, so the circuit structure is concise. The structure can be used for multi-section series battery packs, significantly reducing the chip area. According to the comparison results, the working state of the battery is judged, and corresponding protective measures are taken to achieve the purpose of protecting the lithium battery. The circuit is implement using a 30V 0.18$\mu$ m BCD (Bipolar-CMOS-DMOS) technology. Simulation results show that the overcharge voltage detection accuracy is 0.78mV and the over-discharge voltage detection accuracy is 0.63mV.