The Design Of Battery Protection Monitoring Circuits And Bandgap Voltage Reference Circuits

With the rapid development of portable electronic products, there is an increasing demand for secondary batteries as the source of power, and among them lithium-ion batteries become mainstream products in the secondary battery market for its good performance. However lithium-ion batteries are vulnerable to the damage of abnormal states, such as over-charge, over discharge, over-current, and over-temperature, thereby reducing the efficiency of the battery and shortening battery life, and so lithium-ion battery protection circuit becomes very necessary.Reference voltage source circuit provide high-precision voltage reference for other functional modules in the circuit system, or convert to high-precision current reference providing accurate, stable bias current for other functional models. It is a very important module in analog integrated circuits and hybrid integrated circuits, affecting the overall performance of the whole system. The output reference signal should be stable, realizing the irrelevance to the variations of the supply voltage, temperature and process.In this thesis, we firstly introduce the application mode and basic function of the lithium-ion battery, and then analyze and design the system architecture module division of the protection chip. On the basis of the above the main detection circuit modules have been designed, including over-charge detection module, over discharge detection module, over-current and over-temperature detection modules. In order to meet the need of low power, the MOS transistors in the detection module operate in the sub-threshold region.In this paper, the bandgap voltage reference in insensitive with the variations of the supply power, temperature and process, with a high supply power rejection and low noise. There is a digital control circuit to modify the number of the PNP transistor array, as a soft-trimming to make the voltage more stable and accurate. The simulation results are give, the temperature coefficient is less than 4 ppm/0c. When VDD is 3.3V the PSRR is 89 dB at DC, and it is 64.5 dB at 2.1V at DC. The integrated noise from 100HZ to 100KHZ is 16.8 uVrms. At 2.1V supply voltage the power dissipation is 310 mW, and at 3.3V it is 510 mW.