Analyze the premise and background of low-power lithium-ion battery protection circuits

The necessity of lithium-ion battery circuit protection With the continuous progress and development of science and technology, more and more portable electronic products such as mobile phones, notebook computers, PDAs, digital cameras, etc. continue to appear, which greatly enriches and facilitates people's lives. Now these portable electronic devices have become an indispensable part of people's lives and have very broad market prospects and development space. With the development of these electronic products towards miniaturization, light weight, and portability, higher requirements are put forward for the use of power supplies. Therefore, there is an urgent need for secondary batteries that are small in size, light in weight, and high in energy density. Compared with nickel-cadmium batteries and nickel-hydrogen batteries, lithium-ion batteries have become the most widely used due to their small size, light weight, high energy density, no memory effect, long service life, wide range of use, high working voltage, and low self-discharge rate. Used secondary battery. The basic background and significance of the protection circuit for low-power lithium-ion batteries are introduced. Because of the high energy density of lithium-ion batteries, when the battery is in an overcharged state, the energy will be excessive when the battery temperature rises, so the electrolyte decomposes and gas appears, which is easy to cause internal pressure. Increased and the risk of spontaneous combustion or rupture; on the contrary, in the over-discharged state, the decomposition of the electrolyte causes deterioration of battery characteristics and durability, reducing the number of rechargeable times, and shortening the battery life. Therefore, the protection of lithium-ion batteries is very important, and there must be a battery protection chip in the application of lithium-ion batteries to prevent the battery from overcharging, overdischarging and overcurrent. In summary, the design of lithium-ion battery protection circuits is very important. However, the protection circuit of the lithium-ion battery will increase the additional loss of battery energy and reduce the use time of the battery, which requires the protection circuit of the lithium-ion battery to achieve low power consumption with high accuracy. In addition to the basic functions of overcharge protection, overdischarge protection and overcurrent protection, the lithium-ion battery protection chip should also meet the following requirements, which is also the goal of the chip designed in this article. (1) Ultra-low power consumption. When the lithium-ion battery protection circuit is working, the power consumption is battery loss. Therefore, we must minimize the power consumption of the lithium-ion battery protection circuit. (2) The detection voltage has high accuracy. In order for the protection circuit of the lithium-ion battery to correctly respond to the different working states of the battery, the protection circuit must be able to accurately detect voltage parameters such as overcharge protection voltage and overdischarge protection voltage. (3) It works normally in a large voltage range. Because the power supply voltage of the lithium-ion battery protection circuit is the battery voltage, and the battery voltage can float in a large range, the lithium-ion battery protection circuit must work correctly within the voltage range. Lithium-ion battery protection circuit method Among various batteries currently in use, lithium-ion batteries (also known as lithium-ion secondary batteries or lithium-ion batteries) are a new type of power source developed in recent decades. Different from general chemical power sources, the charging and discharging process of lithium-ion batteries is realized by the insertion and removal of lithium ions in the positive and negative electrodes of the battery. The cathode of a lithium ion battery is a carbon material, such as graphite; the cathode is a transition metal oxide containing lithium, such as lithium cobalt oxide (LiC002). Moreover, the positive and negative materials of lithium-ion batteries are both layered structured compounds with lithium ions intercalated, and can be freely intercalated and separated by lithium ions. The interlayer lithium ions undergo an electrochemical reaction in an appropriate electrolyte. When charging, lithium ions are driven by an external electric field to escape from the positive electrode lattice, pass through the electrolyte, and be embedded in the negative electrode lattice. The discharge process is reversed. Lithium ions return to the positive electrode, and electrons reach the positive electrode through an external circuit to recombine with lithium ions. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Advantages and disadvantages of cobalt-based cathode material LiCoO2 and improvement methods